GIFT   OF 


Engineering 
Library 


INTERNAL  COMBUSTION  ENGINE 

MANUAL 


BY 

F.    W.    STERLING 

Lieutenant  Commander,  U.  S.  Navy,  Retired 


FOURTH    EDITION 
1917 


Library 


COPYRIGHT,   1911 

BY 

F.   W.   STERLING 


COPYRIGHT,  1916 

BY 

F.   W.    STERLING 


COPYRIGHT.   1917 

BY 

F.   W.    STERLING 


WASHINGTON,   D.   C. 

•      BERESFORD,   PRINTER 

1917 


PREFACE  TO  FOURTH  EDITION. 


The  fourth  edition  of  this  volume,  which  marks  its  eighth 
year  as  a  text  book  at  the  Naval  Academy,  has  been  completely 
rewritten,  enlarged  and  brought  up  to  date.  The  original  se- 
quence is  still  preserved,  as  it  is  believed  the  best  for  instruction 
of  the  uninitiated,  viz: 

(a)  The  subject  of  fuels  is  first  treated  fully,  this  being  the 
fundamental  element  that  governs  design  and  operation.     These 
fuels  follow  in  a  natural  sequence  which  order  is  preserved  when 
carburetion  is  taken  up  in  Chapter  V. 

(b)  The  engine  proper  naturally  divides  itself  into  four  sys- 
tems:    (1)  fuel  system,  (2)  ignition  system,  (3)  cooling  system, 
(4)  lubrication  system.    These  are  treated  in  detail  in  the  above 
order  and  in  Chapter  X  the  four  systems  assembled  are  illustrated 
by  modern  commercial  engines. 

A  chapter  has  been  added  on  the  aeroplane  engine  and  the 
five  types,  vertical,  horizontal  opposed,  V-type,  radial,  and  rotary 
are  illustrated  by  up  to  date  American  engines. 

The  author  wishes  to  acknowledge  his  thanks  to  Mr.  J.  G. 
O'Neill,  chemist  at  the  Naval  Experiment  Station,  for  his  aid  in 
enlarging  the  chapter  on  lubrication,  and  to  the  various  manu- 
facturers for  their  aid  in  preparing  the  text  and  cuts. 


INTERNAL  COMBUSTION  ENGINE  MANUAL. 


CHAPTER  I. 
FUELS. 

Selection. — The  considerations  governing  the  selection  of  a 
fuel  in  general  are  its  accessibility,  price,  amount  available,  rate  of 
combustion,  and  thermal  value;  it  does  not  naturally  follow  that 
these  are  the  only  limitations  which  shall  regulate  the  choice  of  a 
fuel  for  use  in  an  internal  combustion  engine. 

Fuel  for  use  in  an  internal  combustion  engine  must  readily 
combine  with  air  to  form  a  combustible  mixture  of  gas  or  vapor, 
must  leave  little  or  no  solid  residue  after  combustion,  and  must 
have  certain  thermo-chemical  characteristics  such  as  a  proper  rate 
of  flame  propagation,  etc.  It  need  not  necessarily  be  of  a  very 
high  calorific  value,  as  will  be  shown  later,  but  obviously  this  is 
desirable.  The  fuel  is  usually  a  compound  of  carbon  and  hydro- 
gen, or  a  mixture  of  such  compounds,  found  thus  in  nature  or 
manufactured. 

The  General  Classification  of  internal  combustion  engine 
fuels  is: 

1.  The  solid  fuels. 

2.  The  liquid  fuels. 

3.  The  gaseous  fuels. 

Solid  fuels  cannot  be  used  in  an  internal  combustion  engine  in 
their  natural  state,  hence  coal  and  other  carbonaceous  solids  must 
be  gasified  to  CO  and  H  by  partial  combustion  and  volatilization 
to  prepare  them  for  such  use.  Although  the  Diesel  engine  was 
originally  designed  to  use  coal  dust  for  fuel,  and  experiments 
have  been  made  along  this  line,  the  idea  was  finally  abandoned. 

Solid  fuels  are  converted  into  (a)  air  gas,  (b)  water  gas,  (c) 
producer  gas. 
I 


*»     ,->  °      "     v">        "*    i         t 

y    f     •*     ?c 


2  INTERNAL    COMBUSTION    ENGINE)    MANUAL. 

Liquid  fuels  comprise  (a)  distillates  of  petroleum  or  crude  oil, 

(b)  alcohol,  and  (c)  benzol. 

The  gaseous  fuels  consist  of  (a)  oil  gas,  (b)  illuminating  gas, 

(c)  coke  oven  gas,  (d)  blast-furnace  gas,   (e)  natural  gas,  and 
(f)  acetylene. 

Of  all  these  fuels  the  most  important  marine  fuel  is  petroleum. 

1.     Solid  Fuels. 

A,  AIR  GAS;  B,  WATER  GAS. 

Air  Gas  is  entitled  to  no  commercial  consideration.  It  can  be 
manufactured  by  the  gasification  of  carbon  by  incomplete  com- 
bustion to  CO  in  a  producer.  The  extremely  low  efficiency  of 
such  a  process  precludes  its  commercial  use. 

Water  Gas. — If  incandescent  fuel  is  sprayed  with  water  vapor, 
the  H2O  is  dissociated  to  H2  and  O,  and  the  latter  combines  with 
the  carbon  in  the  fuel  to  form  CO2  or  CO.  H2  is  liberated.  At 
temperatures  below  1,250°  F.,  CO2  is  formed,  whereas,  if  the 
temperature  be  above  1,800°  F.,  CO  alone  is  formed.  The  pro- 
duction of  water  gas  is  accomplished  in  a  producer.  Its  produc- 
tion is  not  highly  efficient  for  the  following  reasons :  Starting 
with  a  fuel  in  the  incandescent  state,  the  continued  introduction 
of  water  vapor  will  cool  the  producer  and  when  the  temperature 
falls  below  1,800°  F.  an  excessive  amount  of  CO2  is  formed. 
Unless  this  cooling  action  is  counteracted  the  process  will  finally 
cease.  When  the  temperature  becomes  too  low  the  steam  is  shut 
off  and  the  fuel  is  again  brought  to  incandescence  by  blowing 
through  with  air.  During  this  "  blowing  up  "  process  gas  of  a 
low  grade  is  formed.  This  is  rarely  utilized,  and  here  we  find  the 
important  loss  which  accounts  for  the  low  efficiency  of  production. 

C.     PRODUCER  GAS. 

Producer  Gas  is  formed  by  blowing  a  mixture  of  water  vapor 
and  air  through  a  bed  of  incandescent  fuel.  Thus  it  is  a  combina- 
tion of  the  two  previous  gases.  Gas  producers  for  the  generation 


FUELS.  3 

of  this  gas  have  reached  a  high  degree  of  efficiency  and  hold  a 
large  commercial  field.  They  are  used  extensively  in  stationary 
gas  engine  plants  and  in  a  few  instances  have  been  adapted  to 
marine  use.  In  practice,  producer  gas  has  a  net  thermal  value  of 
150  to  180  B.  t.  u.  per  cubic  foot. 

Reactions. — The  fuel  in  the  producer  may  be  divided  into  four 
zones.  That  zone  nearest  the  hearth  consists  of  ash.  The  next 
zone,  called  the  combustion  zone,  is  usually  above  1,900°  F.  Here 
the  carbon  in  the  fuel  is  converted  to  CO2.  In  the  next  zone, 
called  the  decomposition  zone,  the  CO2  from  the  second  zone 
combines  with  the  C  in  the  fuel  to  form  CO.  Also  the  moisture 
in  the  blast  combines  with  the  carbon  in  the  fuel  to  form  CO  and 
H2,  In  the  top  zone  (about  1,300°  F.),  to  which  fresh  fuel  is 
being  constantly  added,  the  volatile  matter  in  the  fuel  is  distilled 
off  and  mixes  with  the  CO2,  and  CO  given  off  from  the  lower 
zones  to  form  producer  gas. 

2.     Liquid  Fuels. 

A.    PSTROLE.UM  AND  ITS  DISTILLATES. 

By  far  the  most  important  fuels  for  marine  internal  combus- 
tion engines  are  derived  from  petroleum.  This  important  product 
is  found  in  nearly  every  part  of  the  globe.  The  United  States,. 
Mexico  and  Russia  produce  most  of  the  petroleum  at  present. 
In  this  country  the  fields  of  Pennsylvania,  Ohio,  Oklahoma,, 
Texas  and  California  are  the  best  producers. 

Contrary  to  the  popular  idea,  oil  is  not  necessarily  found  in  the 
vicinity  of  coal  fields,  but  near  salt  deposits,  the  formation  of  salt 
and  oil  being  apparently  simultaneous.  Although  still  open  to 
dispute,  it  appears  to  be  fairly  well  established  that  petroleum 
was  formed  by  the  decomposition  of  large  masses  of  organic 
matter,  probably  of  marine  origin,  and  the  subsequent  spontaneous 
distillation  of  the  hydrocarbons  from  such  matter.  Some  few 
petroleums  seem  to  be  of  vegetable  origin. 

As  found  in  its  natural  state  its  composition  varies  with  the 
field  of  supply,  but  in  every  case  it  consists  of  C  and  H  with  a 


4  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

small  amount  of  O  and  other  impurities,  the  average  for  13  fields 
being  C  84  per  cent,  H  13;5  per  cent,  O  and  other  impurities, 
such  as  sulphur,  nitrogen  and  metallic  salts,  2.5  per  cent.  The 
greatest  variation  from  this  in  any  one  field  is  2.5  per  cent  C.  Its 
specific  gravity  (considering  only  those  fields  of  commercial 
value)  varies  from  .826  found  in  a  Pennsylvania  field  to  0.956 
found  in  the  Baku  region.  A  field  in  Kaduka,  Russia,  yields  a 
crude  oil  with  the  low  specific  gravity  of  0.65,  and  in  Mexico  an 
oil  is  obtained  with  the  high  specific  gravity  of  1.06. 

Petroleum  may  be  divided  into  two  main  groups,  those  having 
a  paraffin  base  and  those  having  an  asphaltic  base.  The  former 
yields  a  residue  of  solid  hydrocarbons  of  the  paraffin  series,  and 
the  latter  yields  a  residue  rich  in  asphalt.  Certain  of  the  Mid- 
Continent  crudes  contain  both  paraffin  and  asphalt,  so  it  is  ap- 
parent that  the  two  groups  merge. 

Refining. — Since  the  process  of  refining  petroleum  consists  of 
many  intricate  and  seldom  divulged  processes,  it  can  be  described 
only  in  the  most  general  manner.  Different  oils  require  different 
treatment,  and  the  process  varies  depending  upon  the  product  de- 
sired. The  following  is  a  brief  description  of  refining  a  Penn- 
sylvania paraffin  base  crude.  It  is  carried  on  by  fractional  dis- 
tillation, and,  for  convenience,  this  will  be  described  in  two 
stages. 

Fiist  Stage. — Separation  into  groups  by  distillation.  Crude  oil 
is  pumped  into  a  cylindrical  boiler,  called  a  "  crude  still."  When 
this  is  filled  to  a  'certain  level  fires  are  started  underneath  and 
vaporization  and  distillation  commence.  Distillation  as  applied 
to  hydrocarbon  oil,  is  the  separation  of  the  more  volatile  portions 
from  the  less  volatile  portions  by  vaporization,  and  later  con- 
densing them  by  passing  the  hot  vapors  through  a  cooled  tubular 
coil.  Light  hydrocarbons,  such  as  gasoline,  vaporize  very  read- 
ily, whereas  heavy  oils  form  practically  no  vapors  at  atmospheric 
pressure  and  temperature,  therefore  it  is  necessary  to  carry  out 
fractionation  in  a  closed  vessel  in  order  to  accomplish  complete 
separation  of  the  different  fractions.  Since  crude  oil  is  a  com- 
plex mixture  of  hydrocarbons,  each  of  which  has  a  different 


FUELS.  5 

boiling  point,  a  different  temperature  is  required  for  the  vaporiza- 
tion of  each  compound.  The  lightest  hydrocarbons  pass  over 
first  at  the  lowest  temperatures,  and  as  the  temperature  is  in- 
creased heavier  and  heavier  hydrocarbons  are  vaporized. 

Referring  to  Figure  1,  the  vapors  formed  are  led  through  a 
pipe  from  the  still  and  discharged  into  the  base  of  an  aerial  con- 
denser. From  there  they  pass  up  through  alternate  boxes  and 
air-cooled  tubes,  where  products  of  different  boiling  points  are 
simultaneously  condensed  and  thus  automatically  separated  into 
groups.  The  heaviest  hydrocarbons  (heavy  lubricating  distillate) 
condense  upon  striking  the  first  nest  of  air-cooled  tubes,  and, 
dropping  back  into  a  collecting  pan  under  this  nest  of  tubes,  is 
led  by  way  of  a  water-cooled  coil  to  the  storage  tank.  The  next 
heavier  hydrocarbons  (light  lubricating  distillate)  condense  in 
the  second  nest  of  tubes  and  are  conducted  by  way  of  another 
collecting  pan  and  pipe  to  a  second  tank.  Gas-oil  distillate  and 
illuminating-oil  distillate  are  similarly  condensed  in  the  third  and 
fourth  nests  of  tubes,  and  the  naphthas  and  fixed  gases  pass  over 
at  the  top  in  the  form  of  vapor.  The  naphthas  are  condensed 
in  the  water-cooled  coil  in  the  collecting  pipe  and  the  very  light 
hydrocarbons  and  fixed  gases  are  carried  over  to  a  compressor 
(not  shown),  where  the  very  light  hydrocarbons  are  separated 
from  the  "  fixed  gases."  The  object  of  the  water-cooled 
coils  is  to  reduce  the  fractions  below  the  fire  point  to  prevent 
spontaneous  combustion  in  the  tanks.  When  the  residue  is  re- 
duced to  about  15  per  cent  the  fires  are  drawn  and  the  residue, 
crude  cylinder  stock,  is  pumped  from  the  still  through  cooling  coils 
to  a  tank. 

The  steam  connection  shown  in  the  still  is  used  to  allow  steam 
to  bubble  through  the  crude  oil  when  distilling  for  high-quality 
oils.  Due  to  the  mixture  of  oil  and  water  vapors  in  fire  and 
steam  distillation,  oil  vapors  pass  over  at  lower  temperatures 
than  were  fire  used  alone.  The  same  results  are  obtained  by 
placing  the  still  under  a  partial  vacuum  during  the  process.  It 
prevents  the  occurrence  of  "  cracking." 

Cracking. — -Dry   or   destructive    (cracking)    distillation   is   re- 


INTERNAL    COMBUSTION    ENGINE)    MANUAL. 


<  (0  U  O  Ul 


FUELS.  7 

sorted  to  when  a  large  yield  of  gasoline  or  kerosene  is  desired. 
It  is  best  adapted  to  petroleum  which  is  unfit  for  the  manufacture 
of  cylinder  stocks.  The  petroleum  is  fire  distilled,  namely,  dis- 
tilled without  the  use  of  steam.  Temperatures  are  carried  higher 
than  the  normal  boiling  points  of  the  desired  fractions.  Also  the 
still  is  under  more  than  normal  pressure.  The  result  is  dissocia- 
tion of  the  heavier  constituents.  The  heavy  vapors  which  con- 
dense in  the  top  of  the  still  fall  back  into  the  superheated  oil  and 
are  partially  decomposed.  The  resulting  products  are  oils  of 
lighter  gravity  than  would  be  the  case  by  steam  distillation. 

Second  Stage. — Redistillation  and  finishing  the  fractions.  In 
the  first  stage  distillation  there  is  no  sharp  line  of  demarkation 
between  the  different  fractions.  Heavy  constituents  are  carried 
over  mechanically  with  the  lighter  products  and  the  more  volatile 
products  are  mixed  with  the  heavier  parts.  To  completely  sep- 
arate the  fractions  redistillation  is  necessary. 

The  naphtha  distillate  is  divided,  by  redistillation  in  a  steam 
still,  into  the  various  market  grades  of  gasoline. 

The  illuminating-oil  distillate  is  redistilled  in  a  steam  still  to 
eliminate  any  contained  crude  naphtha,  which  is  led  to  the  crude 
naphtha  tank,  the  finished  product  being  kerosene. 

The  other  distillates  are  treated  in  a  similar  manner.  In  the 
case  of  paraffin  base  oils,  the  lubricating  distillates  go  through  a 
process  to  extract  the  paraffin  wax. 

Finishing. — During  or  after  the  redistillation  operations  the 
fractions  must  be  chemically  treated  to  remove  impurities.  The 
fraction  is  :'placed  in  an  agitator,  where  it  is  treated  with  sul- 
phuric acid,  washed  with  water  to  remove  free  acid,  and,  neu- 
tralized with  caustic  soda,  again  washed,  and  the  remaining  water 
settled  out.  In  the  case  of  the  heavier  oils,  steam  coils  in  the 
settling  tanks  aid  this  settling  process  by  temporarily  reducing  the 
viscosity  of  the  oil.  The  final  product  is  filtered  through  fuller's 
earth  to  remove  color-bearing  compounds  and  free  carbon.  The 
finishing  process  removes,  or  decomposes,  aromatic  compounds, 
acids,  phenols,  tarry  products,  sulphur  and  free  carbon. 

Temperatures  at  which  the  Fractions  Distil. — If  the  process 


8 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


were  carried  out  in  a  laboratory  to  obtain  the  distillation  tem- 
peratures of  the  different  petroleum  products  the  results  would 
be  somewhat  as  shown  in  the  table  below : 


Temp. 
(Fahr.) 

Distillate. 

Per  cent. 

Specific 
gravity.* 

Flash  point.* 
(Fahr.) 

Degrees. 

113-140 

Petroleum  ether 

Trace. 

.6 

140-160 
160-250 
250-350 
350 

Gasoline  ) 
Benzine,  naphtha  >  commercial 
Kerosene,  light....  )                  gasoline  
Kerosene  medium 

{         !? 

1      10 

35 

.65 

.70 
.73 
.80 

10 
14 
50 
150 

400 
482 

Kerosene,  heavy  
lubricating  oil 

10 
10 

.89 
.905 

270 
315 

Cylinder  oil  
Vaseline  
Residue  

5 
2 
16 

.915 
.925 

360 

100 

*  Approximately  mean  values. 

The  nomenclature  applied  to  the  petroleum  products  through- 
out the  world  is  so  varied  as  to  become  confusing,  benzine,  naph- 
tha, gasoline  and  kerosene  being  used  very  indiscriminately.  For 
simplicity  we  might  divide  those  products  used  as  fuel  in  the 
internal  combustion  engine  into  (1)  commercial  gasoline  and  (2) 
kerosene  and  the  heavier  petroleum  distillates. 

1.     COMMERCIAL  GASOLINE. 

All  figures  relative  to  the  boiling  point,  specific  gravity,  compo- 
sition, etc.,  must  be  comparative,  for  naturally  the  product  varies 
with  the  field  of  production  of  the  original  crude  oil.  Approxi- 
mately the  range  of  distillation  temperatures  for  commercial 
gasoline  is  115°  to  350°.  At  the  lower  temperature  gasoline  is 
distilled  off,  then,  as  the  temperature  is  increased,  follow  benzine, 
naphtha  and  light  kerosene  in  the  order  named.  Commercial 
gasoline  may  contain  any  or  all  of  these  fractions.  Its  specific 
gravity  varies  from  0.65  to  0.75,  depending  upon  the  proportions 
of  C  and  H  in  its  composition,  and  it  weighs  about  5.9  pounds  per 
gallon.  The  analysis  of  an  ordinary  sample  shows  C  85  per  cent, 
H  14.8  per  cent,  impurities  (principally  O)  0.2  per  cent.  Its  net 


FUELS.  9 

thermal  value  varies  with  the  analysis  around  18,000  B.  t.  u.  per 
pound. 

The  standard  test  for  commercial  gasoline  is  its  specific  gravity. 
Obviously  this  criterion  is  erroneous,  as  the  ultimate  value  of 
gasoline  as  a  fuel  depends  upon  its  volatility.  For  -instance,  a 
high  speed  engine  needs  a  light  fuel,  easily  volatilized,  while  a 
heavy  duty,  slow  speed  motor  can  use  a  much  heavier  fuel.  Were 
the  entire  supply  of  gasoline  derived  from  one  field,  fractions 
obtained  at  the  same  temperatures  would  always  have  the  same 
composition  and  hence  the  same  specific  gravity.  But,  as  the 
world's  supply  is  obtained  from  many  fields  in  which  the  com- 
positions vary,  it  is  possible  to  obtain  two  gasolines  of  widely  dif- 
fering specific  gravities,  which  will  distil  at  the  same  temperature 
and  which  might  be  of  equal  value  as  fuels.  The  volatility  of 
two  gasolines  being  equal,  the  heavier  is  more  efficient  due  to  the 
presence  of  a  higher  percentage  of  carbon.  This  might  appear 
paradoxical  from  the  thermal  view,  but  is  based  upon  thermo 
chemical  considerations. 

At  present  gasoline  holds  the  internal  combustion  engine  field 
as  the  most  important  of  the  petroleum  products.  To  prepare 
gasoline  for  combustion  it  must  be  vaporized,  and  the  ease  with 
which  this  is  accomplished  gives  it  a  decided  advantage  over  all 
other  liquid  fuels.  This  fuel  is  vaporized  or  volatilized  by  passing 
air  over  or  through  the  liquid,  or  by  spraying  the  liquid  into  the 
air  by  force  or  suction.  This  process,  called  carburetion,  will  be 
treated  in  a  later  chapter. 

2.    KEROSENE. 

The  next  heavier  distillate  after  gasoline  is  kerosene.  This  is 
given  off  at  350°  F.  to  400°  F.,  and  has  a  specific  gravity  ranging 
from  0.78  to  0.82.  The  composition  of  a  test  sample  might  run 
C  85.1  per  cent,  H  14.2  per  cent,  O  0.7  per  cent.  Its  net  thermal 
value  is  about  18,500  B.  t.  u.,  and  its  flash  point  is  between  100° 
F.  and  125°  F.  It  is  safer  to  handle  and  stow  than  gasoline,  and, 
being  less  volatile,  does  not  deteriorate  so  rapidly. 


10  INTERNAL,    COMBUSTION    ENGINE    MANUAL. 

It  is  not  so  widely  used  as  an  internal  combustion  engine  fuel 
as  is  gasoline,  for  at  ordinary  temperatures  it  does  not  form  an 
explosive  mixture  with  air,  and  to  render  it  a  suitable  combustible 
requires  special  treatment,  such  as  introduction  into  a  heated 
vaporizer,  or  spraying  into  a  heated  cylinder.  This  will  be 
treated  at  length  under  carburetion.  The  introduction  of  car- 
buretors which  will  handle  either  gasoline  or  kerosene  may  do 
much  to  bring  it  before  the  layman. 

1.  The  Heavier  Distillates.  —  Fuel  oils  have  a  specific  gravity 
of  0.80  to  0.89,  being  of  a  thick  consistency,  have  a  high  flash 
point  and  have  a  heating  value  of  17,000  to  19,000  B.  t.  u.    This 
is  the  fuel  used  in  what  are  known  as  oil  engines.     It  must  be 
sprayed  into  the  hot  cylinder  or  vaporized  in  a  heated  vaporizer. 
Heat  is  imperative  for  its  conversion  to  vapor,  as  it  will  not  form 
a  combustible  vapor  at  ordinary  temperatures. 

2.  Crude  Oil.  —  Crude  oil  is  the  same  thing  as  petroleum  and 
has  been  described  under  that  head.     It  is  used  in  some  motors, 
notably  the  Diesel"  engine,  by  spraying  it  into  the  cylinder  which 
is  partially  filled  with  heated  highly  compressed  air,  but  when  so 
used  the  lighter  oils  are  distilled  off    ("topped")    before    using 
the  crude.    When  crude  oil  is  used  without  previous  topping  the 
lighter  hydrocarbons   are   dissociated   in   the   engine   and   cause 
carbon  deposits. 

B. 


Although  there  are  over  twenty  compounds  known  to  the 
chemist  as  alcohols,  the  most  important  as  a  fuel  is  ethyl  alcohol, 
expressed  by  the  formula  C2H5OH.  Being  a  fixed  compound,  its 
characteristics  cannot  vary  as  in  the  case  of  petroleum  products. 
Absolute  alcohol,  that  is  100  per  cent  pure,  has  a  specific  gravity 
of  0.7946  at  15°  C.,  and  1  gallon  weighs  6.625  pounds.  Its  great 
affinity  for  water  militates  against  the  commercial  article  being 
very  pure. 

Some  years  ago  Congress  removed  the  revenue  on  alcohol  if 
"  denatured,"  and  this  action  was  expected  to  stimulate  alcohol 
engine  development.  The  results  were  discouraging.  This  de- 
naturizing  process  consisted  of  adding  to  the  ethyl  spirit  a  fixed 


FUELS.  II 

amount  of  methyl  or  wood  alcohol  to  render  it  undrinkable,  and 
a  small  percentage  of  benzine  to  prevent  the  redistillation  of  the 
ethyl  spirits.  Congress  prescribed  the  following  formula:  100 
volumes  90  per  cent  ethyl  alcohol,  10  volumes  90  per  cent  methyl 
alcohol,  and  J4  volume  approved  benzine.  Benzine  raises  the 
thermal  value  of  the  mixture.  One  of  the  denaturizing  agents 
required  by  the  laws  of  some  countries  is  benzol.  This  benefits 
the  fuel  by  neutralizing  the  formation  of  acetic  acid  in  the  cylin- 
der during  combustion. 

As  noted  above,  alcohol  is  rarely  found  free  from  water  and  is 
therefore  designated  by  its  percentage  of  purity,  thus,  "  90  per 
cent  alcohol  "  indicates  the  presence  of  10  per  cent  water.  Pure 
alcohol  has  a  thermal  value  of  about  11,600  B.  t.  u.,  and  this 
value  is  reduced  approximately  150  B.  t.  u.  for  each  per  cent  of 
water  present.  From  this  it  might  be  erroneously  concluded  that 
its  thermal  efficiency  as  an  internal  combustion  engine  fuel  is 
lower  than  that  of  gasoline.  Oni  the  contrary,  its  thermal  effi- 
ciency is  higher,  as  alcohol  can  be  more  highly  compressed,  and 
the  dissociation  of  its  contained  water  seems  to  aid  the  expansion 
stroke.  If  equal  weights  of  gasoline  and  alcohol  are  completely 
burned  in  two  motors,  the  latter  will  require  less  air  than  the 
former,  and  consequently  the  heat  losses  in  the  exhaust  gases  are 
less  per  pound  of  fuel  in  the  alcohol  motor. 

Alcohol  is  less  volatile  than  gasoline  and  is  easier  to  handle 
than  kerosene.  It  requires  a  special  form  of  vaporizer,  for  it  will 
not  form  a  combustible  mixture  with  air  at  ordinary  tempera- 
tures. Heat  is  employed  to  aid  in  its  vaporization,  as  will  be 
shown  under  carburetion.  A  mixture  of  equal  weights  of  alcohol 
and  gasoline  forms  a  good  fuel. 

C.     BENZOL. 

Benzol,  C6H6,  is  a  hydrocarbon  by-product  recovered  from  the 
coke  oven,  and  when  distilled  pure  is  a  white  liquid  of  0.88  specific 
gravity  at  15°  C,  with  a  net  thermal  value  of  about  17,300  B.  t.  u. 
It  can  be  used  in  its  natural  state  or  mixed  with  gasoline  in  gaso- 


12  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

line  motors.  As  dyestuff  and  explosive  bases  are  manufactured 
from  benzol,  its  use  as  a  fuel  is  precluded  in  the  present  crisis, 
but  there  is  no  doubt  that  it  will  take  its  legitimate  place  as  a 
motor  fuel  after  the  war. 

3.  The  Gaseous  Fuels. 

A.    OIL  GAS. 

Oil  gas  is  generated  by  vaporizing  crude  oil  by  one  of  two 
distinct  methods,  (1)  the  Pintsch  method,  and  (2)  the  Lowe 
process.  At  present  it  is  used  more  extensively  as  an  illuminating 
gas  than  as  a  gas-engine  fuel.  It  is  largely  employed  for 
municipal  lighting. 

1.  By  the  Pintsch  method  oil  is  led  through  a  retort  which  is 
externally  heated.    A  thin  film  of  oil  is  kept  in  contact  with  the 
heated  surface  and  is  thus  volatilized  into  a  fixed  gas.    It  varies 
considerably  in  composition,  depending  upon  the  original  crude 
oil,  being  a  mixture  of  hydrocarbons  and  free  hydrogen.    Giilder 
gives  one  formula  17.4  per  cent    C2H4,  58.3  per  cent  CH4,  24.3 
per  cent  H,  by  volume. 

2.  The  Lowe  process  employs  a  fire-brick  lined  furnace  con- 
taining a  checker-board  form  of  grating  made  of  fire  brick.    This 
grating  is  heated  to  a  very  high  temperature  by  an  oil-air  blast. 
When  the  desired  temperature  is  reached  the  blast  is  shut  off  and 
the  chimney  is  closed.     An  intimate  mixture  of  crude  oil  and 
superheated  steam  is  now  sprayed  on  to  the  hot  grate  and  (air 
being  excluded)  this  mixture  is  volatilized  into  an  oil  water  gas. 
The  grate  must  be  reheated  periodically.     The  analogy  to  the 
manufacture  of  water  gas  is  apparent.    In  addition  to  the  hydro- 
carbons generated  by  the  Pintsch  method  we  have  N,  O  and  CO 
in  small  quantities  in  gas  made  by  this  method. 

The  process  of  generation  being  completed  by  either  method,  the 
resulting  product  is  washed,  scrubbed  and  purified  by  the  usual 
method.  Although  the  heating  value  per  cubic  foot  of  Pintsch 
gas  is  nearly  40  per  cent  greater  than  that  made  by  the  LoWe 


FUELS.  13 

process,  if  based  upon  fuel  consumption  required  for  manufac- 
ture, their  thermal  values  are  nearly  equal. 

B.     ILLUMINATING  GAS. 

This  gas  is  a  mixture  of  H,  CO,  CH4  and  other  heavy  hydro- 
carbons, O,  N  and  CO,  given  up  by  bituminous  coal  when  it  is 
heated  in  a  retort,  air  being  excluded.  The  residue  is  coke,  tar 
and  ammonia  liquor.  Part  of  this  coke  can  be  utilized  to  heat  the 
retort.  One  ton  of  coal  will  give  off  about  10,000  cubic  feet  of 
gas.  Its  composition  necessarily  varies  widely,  dependent  upon 
the  coal  used  and  the  temperature  of  volatilization.  Its  heating 
value,  which  varies  with  the  composition,  is  about  600  B.  t.  u. 
per  cubic  foot. 

C.  COKE:  OVEN  GAS. 

Coke  is  produced  by  distilling  off  the  volatile  matter  from  coal 
in  a  coke  oven  from  which  air  is  excluded.  The  volatile  matter, 
coke  oven  gas,  contains  hydrocarbons,  hydrogen  and  traces  of 
CO,  N  and  O.  Tar.  ammonia  liquor  and  benzol  are  also  present, 
and  these  are  removed  from  the  gas  by  washing,  forming  valuable 
by-products.  The  gas  is  used  extensively  under  boilers  and  in 
metallurgical  furnaces,  and  is  a  suitable  fuel  for  large  gas  engines. 
Its  thermal  value  varies  from  460  to  500  B.  t.  u.  per  cubic  foot. 

D.  BLAST  FURNACE  GAS. 

The  production  of  pig  iron  is  accompanied  by  the  partial  com- 
bustion of  coke.  The  gas  evolved  during  this  process  can,  after 
suitable  purifying,  be  used  as  a  gas  engine  fuel.  It  contains  about 
5  per  cent  H,  27  per  cent  CO,  very  small  quantities  of  CH4  and 
O,  considerable  CO2  and  about  60  per  cent  N.  Hence  its  heating 
value  is  very  low,  ranging  from  86  to  100  B.  t.  u.  per  cubic  foot. 
Its  use  is  limited  to  iron-making  districts.  Heavy  duty  motors, 
of  large  capacity,  are  manufactured  especially  to  utilize  this  here- 
tofore waste  product.  Blast  furnace  gas  requires  a  high  com- 
pression to  facilitate  ignition  and  combustion. 


14  INTERNAL,    COMBUSTION    ENGINE    MANUAL. 

E.     NATURAL  GAS. 

Natural  gas  is  found  in  or  near  all  oil  fields.  It  is  obviously  a 
volatile  product  of  oil  in  a  natural  state.  Many  towns  light,  heat 
and  receive  power  from  this  source.  Its  use  as  a  gas  engine  fuel 
has  been  developed  more  rapidly  in  this  country  than  abroad.  Its 
composition  varies  with  the  well,  and  even  the  same  well  may  give 
different  results  at  different  times.  Hydrogen  and  hydrocarbons 
are  its  principal  constituents.  The  continued  supply  is  rather 
uncertain  in  any  given  district.  Excessive  H  might  cause  pre- 
ignition,  but,  when  not  too  high  in  H,  it  is  an  excellent  gas-engine 
fuel.  Notwithstanding  the  fact  that  it  has  a  very  high  heat 
value,  it  does  not  develop  as  much  power  as  gasoline  vapor. 

F.    ACETYLENE. 

Acetylene,  C2H2,  has  been  used  experimentally  in  internal 
combustion  engines.  Its  temperature  of  ignition  is  low  and,  since 
it  will  ignite  spontaneously  at  low  pressures,  it  is  unsuitable  for 
use  in  a  high  compression  engine.  It  has  a  high  heat  value  of 
about  18,000  B.  t.  u.  per  pound,  and,  having  a  high  temperature  of 
combustion  and  a  high  rate  of  flame  propagation,  the  energy  de- 
rived from  it  is  high.  Its  cost  of  production  precludes  its  com- 
petition with  other  fuels  at  present.  Liquid  acetylene  has  been 
suggested  as  a  possible  fuel,  but,  as  yet,  extensive  experiments 
have  not  been  conducted  along  this  line. 


CHAPTER  II. 
GENERAL. 

An  internal  combustion  engine,  as  the  name  implies,  is  one  in 
which,  in  contradistinction  to  the  steam  engine,  combustion  of 
the  fuel  takes  place  in  the  cylinder  itself.  A  steam  engine  cannot 
run  without  a  separate  unit,  the  boiler,  for  the  consumption  of 
fuel  and  generation  of  steam,  the  medium  of  motive  power. 
Hence  in  the  gas  engine  vernacular  it  is  called  an  external  com- 
bustion engine.  On  the  other  hand,  fuel  is  fed  directly  to  the 
cylinder  of  an  internal  combustion  engine,  ignited  therein,  and  the 
resulting  explosion  acting  on  the  piston  furnishes  the  motive 
power. 

Progressive  Combustion. — The  internal  combustion  engine  is 
commonly,  though  erroneously,  called  an  explosion  engine.  The 
action  which  takes  place,  and  which  appears  to  be  an  explosion,  is 
in  reality  a  progressive  combustion  and  subsequent  expansion  of 
the  products  of  combustion.  Some  oil  engines  actually  carry  the 
combustion  through  a  considerable  part  of  the  stroke.  Although 
the  expansion  line  of  an  indicator  card  is  necessarily  of  interest 
to  the  manufacturer,  the  ratio  of  expansion  presents  no  problem, 
for  the  internal  combustion  engine  has  no  adjustable  cut-off,  and 
therefore  the  ratio  of  expansion  is  fixed  for  a  given  engine  by  the 
clearance  space  and  the  space  swept  by  the  piston. 

The  problem  of  expansion  is  replaced  by  questions  of  rate  of 
combustion,  rate  of  flame  propagation,  quantity  and  quality  of 
fuel,  and,  most  important  of  all,  compression. 

Compression. — The  question  of  compression  will  be  treated 
at  length  later,  but  a  word  here  is  necessary  to  what  follows : 
when  a  fuel,  such  as  gas,  is  admitted  to  the  cylinder  of  an 
engine,  a  certain  quantity  of  air  is  admitted  at  the  same  time  to 
furnish  the  necessary  oxygen  for  combustion.  Before  ignition 
this  "mixture,"  as  it  is  called,  is  compressed  into  a  small  space 


i6 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


(the  "clearance  space").  This  compression  serves  to  mix 
the  particles  of  air  and  fuel  more  intimately  and  to  raise  the 
temperature  of  the  mixture.  The  resultant  compressed  mixture 
will  ignite  with  more  certainty  and  will  burn  more  evenly  than  a 
rarer  and  colder  mixture. 

There  are  four  essential  systems  to  every  engine,  and  these 
are  treated  at  length  in  subsequent  chapters.  They  are:  (1)  fuel 
system;  (2)  ignition  system;  (3)  cooling  system;  and  (4)  oiling 
system. 

Fuel  System.  —  This  consists  of  a  fuel  tank,  a  strainer  for 
liquid  fuels,  the  carburetor,  atomizer,  or  other  agent  for  convert- 
ing the  fuel  to  a  combustible  vapor,  and  the  exhaust,  which 
usually  terminates  in  a  muffler.  In  the  case  of  liquid  fuels  it  is 
necessary  to  volatilize  and  mix  them  with  air  before  they  can  be 
ignited  in  the  cylinder.  Fig.  2  illustrates  an  ordinary  gasoline 
fuel  system. 


wafer  oc/ffet 


FIG.  2. — Schematic  Plan  of  Marine  Gasoline  Engine  Plant. 

Ignition  System. — If  the  ignition  is  electrical,  this  system  con- 
sists of  a  source  of  current  supply,  wiring,  and  a  means  of  causing 
a  spark  to  leap  a  gap,  thus  forming  an  arc  in  the  presence  of  the 
fuel  in  the  cylinder.  The  spark  thus  created  ignites  the  mixture. 
If  the  system  is  not  electrical,  then  it  consists  of  an  apparatus 
designed  to  bring  the  combustible  mixture  in  contact  with  a  sur- 


GENERAL.  17 

face  hot  enough  to  ignite  it.  This  is  treated  in  detail  under  the 
chapter  on  ignition. 

Cooling  System. — This  consists  of  artificial  means  for  keeping 
the  cylinder  froni  overheating.  It  is  discussed  at  length  later. 

Lubricating  System. — This  is  more  complex  than  in  the  case 
of  the  steam  engine,  as  it  is  necessary  to  include  in  the  system 
means  of  lubricating  the  insides  of  the  cylinder  walls.  It  is  dis- 
cussed in  a  later  chapter  under  the  subdivisions,  internal  and 
external  lubrication. 

The  Four  Requisites. — As  early  as  1832  Beau  de  Rochas  an- 
nounced the  four  requisites  for  economical  and  efficient  working 
of  internal  combustion  engines,  and,  with  one  exception,  these 
are  undisputed  today.  They  are : 

1.  The  maximum  cylinder  volume  with  the  minimum  cooling 
surface. 

2.  The  maximum  rate  of  expansion,  hence,  high  speed. 

3.  The  greatest  possible  pressure  at  the  beginning  of  expansion, 
hence,  high  compression. 

4.  The  greatest  possible  expansion,  hence,  long  stroke. 

Short  and  Long  Stroke. — Much  discussion  has  arisen  on  the 
merits  of  the  long  or  short  stroke  motor.  The  long  stroke  gives  a 
greater  expansion,  but  it  also  increases  the  duration  of  contact  of 
the  gases  with  the  cylinder  walls.  This  increases  the  radiation 
losses.  The  short  stroke  decreases  the  expansion,  but  it  also  de- 
creases the  radiation  losses.  This  point  is  discussed  later. 

COMPARISON    OF    INTERNAL    COMBUSTION    AND 
STEAM   ENGINES. 

Advantages  of  the  Internal  Combustion  Engine. — 1.  Fuel 
Consumption. — The  principal  advantage  of  the  internal  combus- 
tion engine  plant  over  the  steam  plant  is  in  thermal  efficiency. 
The  steam  reciprocating  engine  plant  attains  an  overall  efficiency 
of  from  5  per  cent  to  10  per  cent,  and  the  overall  efficiency  of 
internal  combustion  engine  plants  range  from  17  per  cent  to  30 
per  cent.  Fig.  3  illustrates  the  principal  heat  losses  in  the  two 
2 


18  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

plants.  The  sister  ships,  Kanawha  and  Maumce,  afford  an  excel- 
lent opportunity  of  comparing  these  two  types  of  motive  ma- 
chinery. They  are  employed  on  similar  duty,  use  the  same  fuel, 
and  have  practically  the  same  horse  power.  At  12.5  knots  the 
Maumee,  with  Neurnberg  engines,  burns  about  .5  pound  of  oil 
per  shaft  horse-power  hour,  and  the  Kanawha,  with  reciprocating 
steam  engines,  consumes  about  1.4  pounds  of  oil  per  shaft  horse- 
power hour. 

2.  The  cruising  radius  of  a  vessel  propelled  by  oil  engines  is 
increased  due  to  decreased  fuel  consumption. 

3.  Radiation  or  leakage  losses  in  boiler  and  piping  are  absent 
in  an  internal  combustion  engine  plant,  also  there  are  no  "  stand 
by  "  losses. 

4.  Handling. — The    internal    combustion    engine    is    easier   to 
start  and  stop,  warming  up  not  being  necessary;  the  engine  is 
ready  for  full  load  after  a  few  revolutions. 

5.  Working  force. — In  the  internal  combustion  engine  plant 
labor  is  reduced  and  fewer  attendants  are  needed. 

6.  High  pressures  in  the  internal  combustion  engine  are  present 
only  in  the  cylinders,  which  are  the  only  parts  necessary  to  be 
designed  for  high  pressures. 

7.  Weight  and  space.— -In  small  units,  such  as  launch  installa- 
tions, the  internal  combustion  engine  plant  is  simpler,  more  com- 
pact, and  lighter  than  the  steam  plant,  due  to  the  absence  of  a 
boiler.     In  large  marine  installations  there  is  little  difference  in 
the  weight  and  space  required  for  the  two  types.     Reverting  to 
the  Maumee  (oil  engines)  and  Kanawha  (steam  plant),  the  for- 
mer is  heavier  and  more  costly  than  the  latter,  and  actually  re- 
quires slightly  more  floor  space. 

Disadvantages  of  the  Internal  Combustion  Engine. — 1. 
Waste  of  heat  in  exhaust  gases. — Up  to  date  the  internal  combus- 
tion engine  has  not  been  successfully  compounded,  and  the  utiliza- 
tion of  the  heat  in  the  exhaust  gases  has  long  been  an  unsolved 
problem.  Exhaustive  experiments  have  been  conducted,  and  it  can 
be  stated  on  reliable  authority  that  this  problem  has  reached  a  suc- 
cessful solution,  but  results  cannot  be  published  at  this  time. 


GENERAL.  19 

2.  Waste  of  heat  in  cooling  water. — Whereas  the  steam  engine 
cylinder  is  maintained  at  as  high  a  temperature  as  possible  to  pre- 
vent liquefaction,  this  does  not  hold  in  an  internal  combustion 
engine.    A  large  amount  of  heat  must  be  absorbed  by  the  cooling 
water  to  prevent  overheating  and  consequent  injury  to  the  cylin- 
der, and  the  heat  thus  carried  off  is  a  total  loss.     This  problem 
was  solved  at  the  same  time  that  the  heat  waste  in  the  gases  was 
investigated,  and  these  results  must  also  be  suppressed  for  the 
present. 

3.  Reliability. — The   internal   combustion   engine,   until   recent 
years,  has  not  been  as  uniform  in  its  impulse  and  speed  as  the 
steam  engine  and  has  not  been  considered  as  reliable.    The  latter 
has  been  due  in  part  to  ignorance  on  the  part  of  operators,  and  it 
is  now  safe  to  assume  that  a  well  designed  internal  combustion 
engine  is  as  reliable  as  a  steam  engine.    Developments  in  govern- 
ing have  given  such  uniform  speed  that  alternating  current  gen- 
erators in  parallel  are  driven  by  gas  engines,  and  marine  oil  engine 
plants  are  in  operation  that  leave  little  to  be  desired. 

Summary. — From  the  foregoing  balance  of  advantages  in  favor 
of  the  internal  combustion  engine,  and  from  its  remarkable  over- 
all efficiency,  it  must  not  be  concluded  that  this  type  will  ulti- 
mately supplant  the  steam  engine  and  turbine.  In  a  coking  region 
or  at  a  blast  furnace  plant,  where  a  fuel  supply  is  obtained  from 
an  otherwise  waste  product,  there  can  be  no  question  of  its 
supremacy,  but  for  marine  use  there  have  been  several  inherent 
difficulties  to  overcome. 

Probably  the  most  important  of  these  was  deterioration  due  to 
metallic  disintegration  of  cylinder  walls  from  severe  vibration 
in  the  presence  of  intense  heat.  Also  the  question  of  expansion 
of  the  various  engine  parts,  and  the  inability  to  obtain  castings 
that  will  stand  up  under  the  severe  work,  have  so  far  limited  the 
size  of  cylinders,  and  hence  the  horse-power  per  cylinder.  In 
view  of  the  progress  made  in  solving  these  metallurgical  and  de- 
sign problems  during  the  past  five  years,  it  is  safe  to  predict  that 
the  internal  combustion  engine  may  be  developed  to  very  large 
sizes  in  the  not  distant  future. 


20  INTERNAL    COMBUSTION    ENGINE)    MANUAL. 

The  ideal  condition  of  an  impulse  per  cylinder  per  stroke, 
which  is  present  in  the  steam  engine,  is  not  attained  in  the  in- 
ternal combustion  engine  except  in  one  case,  that  of  the  double 
acting  tandem  engine,  which  cannot  be  used  in  all  kinds  of  work. 
Only  one  impulse  is  received  for  each  two  or  four  strokes  in  a 
single  cylinder  engine,  and  the  engine  must  be  multicylinder  to 
get  a  continuous  impulse.  Six  cylinders  is  the  least  number  that 
will  furnish  an  overlapping  impulse  if  the  engine  be  four  cycle. 

Heat  Balance. — A  table  accounting  for  the  heat  furnished  to 
an  internal  combustion  engine  is  called  the  heat  balance.  From 
the  diagram,  Fig.  3,  such  a  heat  balance  might  be  constructed. 
Generally  the  heat  is  accounted  for  under  four  items : 

1.  Heat  of  indicated  work. 

2.  Heat  loss  to  circulating  water. 

3.  Heat  lost  in  exhaust  gases. 

4.  Heat  of  radiation,  conduction,  etc. 

Such  a  balance  for  the  engine  under  consideration  would  be : 

Heat  converted  into  mechanical  energy.  . .  .  23.0% 

Heat  lost  to  circulating  water 24.0% 

Heat  lost  in  exhaust  gases. 33.0% 

Heat  lost  by  radiation,  conduction,  etc 20.0% 


100.0% 

Items  one  and  two  can  be  determined  accurately.  The  deter- 
mination of  item  three  is  difficult  and  involves  the  weight  of  the 
exhaust  gases  and  their  specific  heats  at  the  temperature  of  the 
exhaust.  Item  four  is  the  difference  between  the  heat  supplied 
and  the  sum  of  the  other  three  items.  Sometimes  the  heat  bal- 
ance is  made  up  of  three  parts  by  combining  items  three  and  four. 


GENERAL. 


Internal  Combustion  Engine  Plant. 
Diagram  of  Heat  Losses  per  Ib.  of  Fuel. 


Overall  Efficiency 


=  19.3  per  cent. 


Steam  Reciprocating  Engine  Plant. 
Diagram  of  Heat  Losses  per  Ib.  of  Fuel. 


Overall  Efficiency 

J 


15000 


=  8.7  per  cent. 


FIG.  3. — Distribution  of  Heat  Energy  in  Steam  and  Internal  Combustion 

Engine  Plants. 


22  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

Development. — The  rapid  strides  in  the  development  of  the 
internal  combustion  engine  are  due  in  a  large  measure  to  the 
demands  of  pleasure  in  addition  to  the  needs  of  industry.  The 
automobile  industry  has  developed  the  high-speed  motor  to  a 
very  high  state  of  efficiency,  The  aeroplane  was  made  possible 
by  the  gasoline  engine,  all  the  other  problems  of  human  flight 
having  been  solved  years  before  suitable  motive  power  was 
available.  On  the  other  hand,  the  industrial  world  was  not  be- 
hind in  developing  the  slow-speed,  heavy-duty  motor,  and  we 
now  find  internal  combustion  engines  employed  for  every  con- 
ceivable duty  from  aeroplane  propulsion  to  furnishing  the  motive 
power  for  agricultural  machinery. 

For  marine  use,  gasoline  and  oil  engines  have  proved  their 
efficiency  in  small  units,  such  as  launches,  submarine  chasers, 
etc.,  and  recent  internal  combustion  engine  installations  on  large 
ships  have  been  attended  with  complete  success.  The  largest  oil 
engined  motor  ship  thus  far  built  in  the  United  States  is  the 
twin-screw  Naval  collier  Maumee,  of  14,500  tons  displacement, 
propelled  by  two  single-acting  two-cycle  Diesel  engines  of  2,500 
shaft  horse-power  each. 


CHAPTER  III. 


CONSTRUCTION. 

The  subject  of  internal  combustion  engine  construction  will 
have  to  be  treated  in  a  very  general  manner  because  of  the 
variety  of  forms  of  all  the  parts  found  in  different  types.  Nat- 
urally the  design  of  engine  depends  upon  the  service  it  is  intended 
to  perform,  thus,  the  aeroplane  engine  is  constructed  in  this 
country  to  weigh  as  little  as  three  and  one-half  pounds  per  horse- 
power, whereas  engines  for  marine  use  weigh  from  45  to  60 
pounds  per  horse-power  for  launches,  and  as  high  as  350  pounds 
per  horse-power  for  large  marine  plants.  With  the  many  types 
existing  it  is  only  possible  to  give  a  few  general  forms  of  parts. 

Cylinder. — Cylinders  may  be  cast  singly  or  en  bloc,  that  is,  in  a 
multicylinder  engine  each  cylinder  may  be  cast  as  a  separate  unit 
or  two  or  more  may  be  cast  in  one  piece.  They,  are  generally 
classified  as  (1)  water  cooled  and  (2)  air  cooled,  depending  upon 


1 

1 

1 

1 

FIG.  4.— Water  Cooled,  Four 
Cycle  Cylinder. 


FIG.  5.— Air  Cooled,  Four 
Cycle  Cylinder. 


24  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

the  system  adopted  to  prevent  overheating  of  the  cylinder.  Fig.  4 
shows  a  water  cooled  cylinder  with  the  annular  space  in  which  to 
circulate  water.  Fig.  5  shows  an  air  cooled  cylinder.  The  ribs 
cast  on  the  outside  of  this  cylinder  increase  the  radiating  surface 
of  the  cylinder  and  thus  serve  the  same  purpose  as  the  circulating 
water  in  the  other  type.  It  should  be  noted  that  the  annular  space 
and  the  ribs  do  not  extend  the  full  length  of  the  cylinder,  but  only 
cover  the  upper  part.  They  only  extend  a  little  below  the  com- 
pression space,  which  is  the  hottest  part  of  the  cylinder.  Fig.  6 
shows  a  water  cooled  cylinder  with  a  copper  water  jacket  fastened 


FIG.  6.— Copper  Jack- 
eted Cylinder. 


FiG.  7. — Pair  of  Cylinders  Cast 
en  bloc. 


and  caulked  to  the  cylinder.  The  corrugations  shown  allow  for 
the  unequal  expansion  of  the  copper  of  the  jacket  and  the  iron  of 
which  the  cylinder  is  cast.  This  construction  is  the  more  ex- 
pensive of  the  two  and  is  only  used  in  automobile  and  aeroplane 
engines.  Copper  water  jackets  may  be  electrically  deposited  as 
follows :  After  the  cylinder  is  machine  finished  a  wax  mold  is 
built  on  its  outer  surface  to  conform  to  the  shape  of  the  water 
jacket.  This  wax  mold  is  coated  with  a  graphite  conducting  film 
and  the  whole  placed  in  a  copper  plating  bath.  When  copper  is 
deposited  to  the  requisite  thickness  the  cylinder  is  removed  from 


CONSTRUCTION.  25 

the  bath,  the  wax  mold  is  melted  out  by  low  heat,  and  the  space 
formerly  occupied  by  the  wax  becomes  the  water  jacket  space. 
Fig.  7  illustrates  a  pair  of  cylinders  cast  en  bloc. 

Cylinders  are  made  of  close  grain,  gray  cast  iron,  hardness 
being  .the  essential  requisite.  The  previous  four  illustrations 
portray  the  four  cycle  type  engine ;  Fig.  8  shows  the  general  type 
of  two  cycle  cylinder  without  valves ;  the  piston  passing  over  the 
port  openings  acts  as  a  valve.  The  cylinders  are  counterbored  at 
the  ends  of  the  stroke.  This  prevents  the  formation  by  the 
piston  ring  of  a  collar  at  each  end  of  its  travel. 


FIG.  8.— Two  Cycle  Water  Cooled  Cylinder. 

Piston. — The  majority  of  internal  combustion  engines  are 
single  acting,  receiving  the  impulse  on  only  one  end  of  the  piston. 
The  impulse  is  much  more  sudden  than  in  the  case  of  the  steam 
engine,  and  if  the  piston  were  constructed  disc  shaped,  as  in  the 
steam  engine,  there  would  be  a  tendency  to  cant  or  dish  on  the 
explosion  stroke.  For  this  reason  and  for  the  purpose  of  aiding 
packing,  cooling  and  guiding  generally,  the  piston  is  made  long 
and  hollow,  the  length  for  a  good  four  cycle,  high-speed  design 
being  about" one  and  one-half  times  the  diameter.  In  this  type  the 
length  precludes  the  necessity  for  connecting  rod  and  guides. 


26 


INTERNAL    COMBUSTION    ENGINE)    MANUAL. 


The  piston  tapers,  the  explosion  end  being  slightly  smaller,  say 
.001  of  the  diameter,  than  the  opposite  end.  The  reason  for  this 
is  that  the  explosion  end,  being  in  contact  with  the  hot  gases,  when 
running,  will  expand  more  than  the  other  end.  It  is  fitted  with 


FIG.  9. — Piston,  Showing  Method  of  Securing 
Connecting  Rod. 

eccentric  rings,  usually  four,  which  spring  into  grooves  shown  in 
Fig.  9,  the  lowest  ring  acting  as  an  oil  ring.  Fig.  10  shows  a 
piston  with  rings,  connecting  rod  and  bearings,  all  assembled. 
Heavy  duty  and  double  acting  engines  have  different  types  of 


FIG.  10. — Piston  with  Rings,  Connecting  Rod 
and  Bearings  Assembled. 

pistons,  some  being  of  such  a  form  as  to  require  piston  rods, 
connecting  rods  and  guides.    These  are  illustrated  in  Chapter  X. 
Figs.  11  and  12  are  two  types  of  piston  heads  for  two  cycle  en- 
gines.   The  dished  head,  Fig.  11,  and  the  web  cast  on  top  of  the 


CONSTRUCTION. 


piston,  Fig.  12,  serve  to  deflect  the  incoming  gases  and  thus  aid  in 
scavenging  the  cylinder. 

Connecting  Rod  and  Wrist  Pin. — In  all  engines,  except  the 
large  stationary  ones,  the  piston  rod  is  absent,  the  piston  motion 
being  communicated  to  the  crank  direct  by  the  "  connecting  rod." 
At  the  piston  end  the  rod  is  connected  to  the  "  wrist  pin."  There 
are  two  ways  of  forming  this  bearing;  first — the  one  most  com- 
monly used — the  wrist  pin  is  locked  fast  to  the  piston,  the  rod 
working  on  it ;  and  second,  the  rod  is  locked  fast  to  the  wrist  pin 


FIG.  ii. 


FIG.  12. 


Two  Cycle  Piston  Heads. 


and  the  pin  works  in  the  piston  as  a  bearing.  Fig.  9  illustrates 
the  first  method,  a  set  screw  and  lock  nut  being  shown  in  place. 
Rods  are  forged  of  drop  forged  steel,  the  heavy  stationary  en- 
gines having  rods  of  rectangular  section  and  the  marine  and 
lighter  engines  having  an  "  I  "  section  rod. 

Valves. — The  most  common  and  best  developed  valve  at  present 
is  the  disc,  poppet  valve  shown  in  Fig.  13.  Drop  forged  valves 
answer  the  purpose  for  all  but  the  heavier  engines,  which  require 
valves  cast  in  one  piece.  The  best  material  must  be  used  in  valves, 
especially  the  exhaust,  as  they  are  subject  to  the  intense  heat  of 


28 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


explosion,  and  the  exhaust  valves  receive  the  full  erosive  effect  of 
the  fast  moving,  hot  exhaust.  The  smaller  valves  have  a  slot  in 
the  head  to  fit  a  screw-driver  -or  tool  for  regrinding  to  the  seat. 

The  requirements  for  an  efficient  valve  are :  ( 1 )  it  must  be  gas 
tight  without  excessive  friction;  (2)  the  opening  and  closure 
must  be  instantaneous;  (3)  it  must  be  accessible  for  cleaning, 
grinding,  etc. ;  (4)  the  gases  must  not  be  wire  drawn. 

The  exhaust  valve  is  generally  actuated  by  cam  gear  situated 
on  a  countershaft  that  is  geared  to  the  main  shaft.  This  is  also 
the  better  method  for  actuating  the  admission  valve,  although 
some  engines  are  fitted  with  spring  loaded  admission  valves  that 
lift  automatically  on  the  suction  stroke.  In  some  designs  a  rod 
and  rocking  lever,  actuated  by  a  cam,  opens  alternately  both 
admission  and  exhaust  valves  of  the  same  cylinder.  The  Curtis 
engine  and  many  motorcycle  engines  are  of  this  type. 


FIG.  13.— Conical  Disc,  Poppet  Valve. 

There  are  a  variety  of  novel  valves,  such  as  rotating  valves, 
that  have  not  received  general  recognition.  The  Knight  motor 
(Chapter  X)  has  two  reciprocating  sleeves  between  the  piston 
and  the  cylinder.  These  sleeves  contain  openings  that  cover  and 
uncover  the  port  openings  at  the  proper  points  of  the  cycle  and 
thus  act  alternately  as  admission  and  exhaust  valve.  The  larger 
exhaust  valves  are  hollow  to  permit  circulation  of  water  for 
cooling  the  valve. 

Push  Rods. — Interposed  between  the  valve  stem  and  the  cam 
on  the  countershaft  is  a  push  rod,  Fig.  14.  As  seen  in  Fig.  18, 
these  are  carried  in  guides  that  fasten  to  the  engine  base.  On 
the  lower  end  is  a  hard  steel  roller  that  bears  on  the  cam,  giving 


CONSTRUCTION. 


minimum  friction.  In  the  latest  practice  for  high  speed  engines 
the  top  of  the  push  rod  has  an  adjustable  screw  that  bears  on  the 
valve  stem  so  that  wear  on  the  end  of  the  rod  can  be  compensated ; 
this  tends  toward  quiet  running,  and  aids  valve  timing. 

Fly- Wheel. — On  account  of  the  intermittent  impulse  given  an 
internal  combustion  engine  shaft,  all  engines  having  six  or  less 
working  cylinders  require  a  fly-wheel.  By  its  inertia  it  tends  to 
give  a  uniform  rotation  to  the  shaft  in  spite  of  the  non-uniform 
crank  effort.  Obviously,  the  relative  size  of  fly-wheel  required  in- 
creases with  the  decrease  in  the  number  of  working  cylinders. 

fa/ve  Stem 
Pushftod-  - 


Roller 


Counter  Shaft 

FIG.  14. — Push  Rod. 


The  same  features  govern  fly-wheel  design  whether  for  internal 
combustion  or  other  engines,  except  that  more  care  must  be  taken 
in  the  balance  of  those  used  in  this  particular  field. 

Balancing  the  Crank  Arm. — Single-throw  cranks  for  high- 
speed engines  are  provided  with  balance  weights  to  balance  the 
weight  of  the  crank  pin,  web,  and  that  part  of  the  connecting  rod 
that  is  regarded  as  rotative.  These  weights  are  generally  located 
on  both  crank  webs,  and  must  be  securely  fastened,  because  any 
play  between  them  and  the  web  would  rapidly  increase  from  the 
engine  vibration  and  would  cause  serious  trouble.  The  counter- 
weights for  small  shafting  are  made  integral  with  the  crank  web. 


30  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

Muffler. — For  quiet  operation  the  muffler  is  an  essential  part  of 
the  exhaust  system.  Exhausting  into  the  atmosphere  at  the 
normal  exhaust  pressure  causes  a  sharp,  disagreeable  noise.  This 
is  so  annoying  that  many  municipalities  have  passed  ordinances 
requiring  that  all  internal  combustion  engines  be  fitted  with 
mufflers. 

A  muffler  is  merely  an  enlargement  near  the  end  of  the  exhaust 
line  to  allow  a  gradual  expansion  of  the  exhaust  gases  to  the  at- 
mospheric pressure.  Though  there  are  a  variety  of  forms^  the 
principle  is  the  same  in  all.  Cast  iron  is  generally  used  in  con- 
struction, as  this  best  resists  the  corrosive  effects  of  the  hot  gases. 

Some  mufflers  are  fitted  with  baffles,  and  in  this  case  care  must 
be  taken  in  the  design  to  prevent  a  back  pressure  in  the  exhaust. 
A  properly  designed  muffler  will  reduce  the  pressure  at  the  muffler 
exit  without  reducing  the  speed  of  the  exhaust  from  the  engine 
to  the  muffler.  As  long  as  this  speed  is  maintained  no  back 
pressure  will  result.  In  stationary  plants  water  spray  is  some- 
times injected  into  the  muffler.  This  is  standard  marine  practice. 


FIG.   15.— Gas  Pipe  Muffler. 

The  gas  pipe  muffler,  Fig.  15,  illustrates  the  muffler  principle. 
It  consists  of  a  perforated  exhaust  nozzle  within  a  larger  open 
end  pipe.  The  exhaust  puffs  pass  through  the  perforations  and 
expand  into  the  larger  pipe,  passing  out  at  the  end  at  a  more  even 
pressure. 

The  marine  type  muffler,  Fig.  16,  is  a  water  cooled  type.  The 
cooling  water  entering  through  the  top  inlet,  flows  over  the  cooling 
plate  on  which  the  entering  gases  impinge.  The  gases  are  satu- 
rated with  water  vapor,  lowering  their  temperature  and  reducing 


CONSTRUCTION. 


their  volume.  The  saturated  gases  strike  the  mixing  plate  and 
flow  into  the  expansion  chamber  through  openings  at  the  mixing 
plate  edge.  They  leave  the  muffler  through  the  perforated 
silencing  sleeve  at  a  steady  pressure. 


Coo/ing  fl/ofe 


Water  outlet. 


/6. 


Type  Muff/er 


The  ejector  muffler,  Fig.  17,  is  designed,  as  its  name  implies, 
on  the  principle  of  an  ejector.  It  consists  of  three  expansion 
chambers  which  are  formed  by  conical  baffle  plates,  perforated  top 
and  bottom,  arranged  in  two  sets.  The  central  pipe,  leading 
through  the  muffler,  is  of  varying  diameter  and  a  part  of  the  gas 
entering  the  muffler  passes  directly  into  the  center  chamber  and 


Outlet 


FIG.  17. — Ejector  Muffler. 

through  the  second  set  of  cones  before  the  gas  which  has  entered 
the  first  chamber  has  passed  through  the  first  set.  A  portion  of 
the  gas  is  conducted  straight  through  the  center  pipe  to  the 
nozzle  at  a  high  velocity  which  creates  a  partial  vacuum  in  the 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


CONSTRUCTION. 


33 


third  chamber.  The  rapid  forward  movement  of  the  gas  through 
the  first  and  second  chambers  to  the  third  causes  a  sudden  expan- 
sion, removing  the  heat  from  the  gas  and  reducing  the  pressure 
in  the  muffler  to  below  that  of  the  atmosphere.  This  allows  the 
gas  to  escape  without  noise  and  without  back  pressure.  This 
type  was  invented  to  increase  the  efficiency  of  automobile  mufflers, 
but  it  is  adapted  to  marine  use  with  cooling  water. 

Countershaft  for  Multicylinder  Engine. — In  a  multicylinder 
engine  where  there  are  numerous  valves,  etc.,  to  be  actuated  by 
cams,  a  countershaft,  sometimes  called  the  cam  shaft,  is  fitted. 
This  is  a  small  shaft,  running  the  length  of  the  engine,  parallel  to 
and  geared  to  the  engine  main  shaft.  In  addition  to  actuating 
all  the  valves  this  shaft  sometimes  actuates  the  timer,  pumps, 
etc.  It  is  geared  to  the  main  shaft  of  a  four  cycle  engine  in  the 
ratio  of  one  to  two  because  each  operation  at  any  one  valve  must 
take  place  every  second  revolution.  Fig.  18  shows  the  counter- 
shaft as  operating  in  a  marine  or  other  high-speed  engine.  It  is 
made  of  the  best  nickel  steel.  Engines  designed  with  admission 
and  exhaust  valves  on  opposite  sides  of  the  cylinders  require  two 
countershafts. 


FIG.   19.— Underwater  Exhaust. 

Underwater  Exhaust. — Fig.  19  illustrates  a  common  form  of 
exhaust  below  the  water  line.  In  this  case  there  are  two  outlets 
from  the  muffler.  This  form  is  a  little  more  expensive  than  that 
with  one  outlet,  but  it  is  used  considerably  with  the  ejector  muffler. 

3 


CHAPTER  IV. 
TYPES,  CYCLES,  ETC. 

Cycles. 

"  A  cycle  in  engineering  is  any  operation  or  sequence  of  opera- 
tions that  leaves  the  conditions  the  same  at  the  end  that  they  were 
in  the  beginning."  An  internal  combustion  engine  cycle  con- 
sists of:  (1)  suction  or  admission  of  the  charge;  (2)  compres- 
sion; (3)  ignition,  combustion  and  expansion ;  (4)  exhaust.  The 
number  of  strokes  necessary  to  complete  this  cycle  gives  a  means 
of  cyclic  classification  as  follows:  (1)  two-stroke  cycle;  (2)  four- 
stroke  cycle.  The  common  terms  for  these  are  two  cycle  and 
four  cycle.  The  latter  is  sometimes  called  the  Beau  de  Rocha 
cycle,  or  more  commonly  the  Otto  cycle.  The  two  cycle  is  some- 
times called  the  Clerk  cycle. 

Four-Stroke  Cycle. 

Figs.  20  to  23,  inclusive,  illustrate  the  four  strokes  forming  a 
complete  cycle  in  a  four  cycle  engine.  The  piston  is  shown  near 
the  finish  of  the  stroke  in  each  case.  The  admission  valve  com- 
municates with  the  source  of  fuel  supply. 

Admission. — In  Fig.  20  the  piston  has  traveled  one  down 
stroke.  During  this  stroke  the  admission  valve  is  open  and  the 
vacuum  formed  by  the  down  stroke  of  the  piston  has  been  filled 
by  the  inrush  of  a  fresh  charge  of  combustible  mixture.  This  is 
called  the  suction  or  aspiration  stroke.  The  admission  valve 
closes  at  the  end  of  this  stroke. 

Compression,  Fig.  21. — During  this  up  stroke  both  valves  are 
closed  and  the  charge  is  compressed  into  a  small  space  at  the 
cylinder  end  called  the  "  clearance  space."  The  necessity  for 
compression  will  be  shown  later. 


TYPES,    CYCLES,    ETC. 


35 


Ignition,  Fig.  22. — This  third  stroke  is  the  power  stroke  and 
is  variously  known  as  the  ignition,  combustion,  expansion,  or 
explosion  stroke.  During  this  stroke  both  valves  are  closed.  At 
the  beginning  of  the  stroke  the  charge  is  ignited  and  the  subse- 
quent expansion  furnishes  the  motive  impulse  to  the  piston,  driv- 
ing it  to  the  end  of  its  stroke. 


1.  Admission  Valve. 

2.  Exhaust  Valve. 

Periods  in  the  Cycle  of  a  Four  Cycle  Engine. 

Exhaust,  Fig.  23. — The  exhaust  valve  opens  at  or  near  the 
end  of  the  expansion  stroke  and  the  up  travel  of  the  piston  on 
this  fourth  stroke  forces  the  gases  of  combustion  out  of  the 
cylinder  completing  the  cycle. 

As  the  engine  receives  only  one  impulse  every  fourth  stroke 
means  must  be  employed  to  drive  the  engine  throughout  the 
remaining  three.  A  fly-wheel,  which  accomplishes  this  by  its 
inertia,  is  installed  on  the  main  shaft.  In  the  case  of  multi- 
cylinder  engines  the  fly-wheel  by  its  inertia  balances  the  impulses 
and  gives  a  steady  speed. 


36  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

Two-Stroke  Cycle. 

The  two  cycle  engine  requires  only  two  strokes  or  one  revolu- 
tion to  complete  the  cycle.  As  seen  from  Fig.  24,  the  crank  case 
is  closed  gas  tight  and  a  spring  loaded  admission  valve  opens  to 


FIG.  24.  FIG.  25. 

Periods  in  the  Cycle  of  a  Two-Cycle  Engine, 
Two-Port  Engine. 

the  crank  case.  Instead  of  the  admission  and  exhaust  being 
regulated  by  valves,  port  openings  in  the  cylinder  sides  are  uncov- 
ered by  the  piston  at  proper  points  in  the  stroke  and  these  open- 
ings communicate  with  the  fuel  supply  ajid  the  exhaust  passage. 
There  are  two  general  designs  of  the  two  cycle  engine,  (1)  two 
port  engine,  (2)  three  port  engine.  The  two  cycle  engine  is 
sometimes  called  a  valveless  engine  on  account  of  the  absence  of 
valves.  As  the  piston  receives  an  impulse  every  other  stroke,  a 
fly-wheel  is  employed  to  drive  the  piston  through  the  non-impulse 
stroke. 


TYPES,    CYCLES,    ETC.  37 

Two  Port  Engine. — The  port  a,  Fig.  24,  connects  the  crank 
case  and  cylinder  around  the  piston,  when  at  the  bottom  of  its 
stroke.  Deflecting  plate  b  aids  in  scavenging  the  cylinder. 

Two  circles  in  the  crank  case, -Fig.  24,  illustrate  the  steps  in 
the  cycle.  The  inner  circle  indicates  operations  in  the  crank 
case  and  the  outer  circle  indicates  simultaneous  periods  in  the 
cycle  on  top  of  the  piston. 

Working  Stroke. — Starting  from  the  position  shown  in  Fig. 
24,  the  charge  is  compressed  in  the  top  of  the  cylinder  and  has 
just  been  ignited.  The  crank  case  is  full  of  a  fresh  charge  that 
has  just  been  drawn  through  the  admission  valve.  The  piston  is 
driven  down  by  the  expansion.  The  port  d  being  covered,  the 
charge  in  the  crank  case  is  compressed  on  the  down  stroke. 
Expansion  takes  place  in  the  cylinder  to  the  point  1  and  when 
this  point  is  reached  by  the  crank,  the  exhaust  port  is  uncovered 
relieving  the  pressure.  At  the  point  2,  port  d  is  opened  allowing 
communication  between  the  crank  case  and  the  cylinder.  The 
compressed  charge  in  the  crank  case  rushes  into  the  cylinder 
displacing  the  exhaust  gases  which  escape  through  the  exhaust 
port  e,  Fig.  25. 

Compression  Stroke. — On  the  return  stroke  when  the  point  3 
is  reached  port  d  is  covered  by  the  piston  and  the  up  travel  of 
the  piston  creates  a  vacuum  in  the  crank  case,  which  opens  the 
admission  valve,  and  sucks  a  fresh  charge  into  the  crank  case.  At 
the  point  4  the  exhaust  port  is  covered  and  from  this  point  to 
point  5  the  fresh  charge  on  top  of  the  piston  is  compressed.  At 
point  5  ignition  takes  place,  completing  the  cycle.  At  6  the 
spring  loaded  admission  valve  to  the  crank  chamber  closes. 

Three  Port  Engine.— The  Navy  Type  Engine,  Figs.  26  and 
27,  is  a  good  example  of  the  three  port  engine.  This  engine  does 
not  require  a  spring  loaded  admission  valve  between  the  crank 
case  and  the  carburetor.  A  third  port  (5)  takes  its  place.  The 
cycle  is  as  follows : 


38  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

W 'or king  Stroke. — Starting  with  the  piston  (1)  at  the  top  of 
its  stroke,  Fig.  26,  the  combustible  charge  of  gas  is  compressed 
and  ready  for  ignition.  On  the  down  stroke  the  charge  in  the 
combustion  chamber  (2)  is  ignited  by  the  spark  (3)  and  burned, 
and  the  resulting  pressure  forces  the  piston  downward.  At  the 
beginning  of  this  stroke  the  crank  case  (4)  is  full  of  combustible 
mixture  that  has  been  drawn  in  through  the  ports  ( 5 ) ,  and  which 
is  compressed  to  about  five  pounds  by  the  piston  on  its  down 
stroke.  When  near  the  bottom  of  the  stroke,  the  top  edge  of  the 
piston  uncovers  a  series  of  ports  (6)  in  the  cylinder  wall  through 
which  the  burned  gases  escape  to  the  exhaust  pipe,  the  pressure 
in  the  cylinder  dropping  to  about  atmospheric.  Shortly  after  the 
exhaust  ports  (6)  have  been  uncovered,  the  piston,  still  moving 
downward  uncovers  the  transfer  ports  (7)  in  the  cylinder  wall. 
These  are  situated  diametrically  opposite  the  exhaust  ports.  The 
transfer  of  the  mixture  from  the  crank  case  to  the  cylinder  is 
made  through  ports  (8)  in  the  piston.  These  register  with  the 
ports  (9)  in  the  cylinder  wall  and  admit  the  mixture  into  the 
by-pass  (10),  from  whence  it  passes  into  the  cylinder  through 
ports  (7).  Ports  (7)  and  (9)  open  and  close  simultaneously. 
To  prevent  the  incoming  charge  from  passing  directly  across  the 
cylinder  and  out  of  the  exhaust  ports  (6),  transfer  and  exhaust 
ports  being  open  at  the  same  time,  the  top  of  the  piston  is  pro- 
vided with  a  baffle  or  deflector  plate  (11)  which  deflects  the 
charge  up  to  the  top  of  the  cylinder,  thus  aiding  scavenging. 

Compression  Stroke. — On  the  up  stroke,  Fig.  27,  the  piston 
first  closes  the  transfer  ports  (7)  and  shortly  after  the  exhaust 
ports  (6).  The  charge  in  the  cylinder  is  compressed  and  at  the 
top  of  the  stroke  is  ready  for  firing.  During  this  stroke  a  new 
charge  is  drawn  into  the  crank  case  through  ports  (5)  in  the 
cylinder  wall.  Ports  (5)  are  uncovered  by  the  bottom  edge  of 
the  piston  (1)  when  at  the  top  of  its  stroke. 


TYPES,    CYCLES,    ETC. 


39 


4O  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

Advantages  and  Disadvantages  of  the  Two  Cycles. 

Two  Cycle. — Advantages. — No  valves,  valve  gear,  cams  and 
cam  shaft ;  more  uniform  turning  moment  and  lighter  fly-wheel ; 
smaller  cylinder  volume  per  unit  of  power;  simplicity  and  com- 
pactness. 

Disadvantages. — Loss  of  fresh  fuel  with  exhaust  reduces  the 
economy;  crank  case  must  be  kept  gas  tight  to  prevent  loss  of 
fuel  and  compression ;  fresh  fuel  entering  the  cylinder  full  of  hot 
exhaust  gases  may  cause  premature  explosion,  and  if  this  occurs 
before  the  admission  port  is  closed,  the  crank  case  charge  may 
explode,  causing  considerable  damage  to  the  engine.  For  large 
engines  an  auxiliary  pump  is  employed  to  replace  crank  case 
compression. 

Four  Cycle. — Advantages. — Better  explosion  control;  more 
economical;  compression  not  dependent  upon  tightness  of  any 
part  except  valves  and  piston  rings ;  no  auxiliary  pump  required ; 
gas  tightness  of  crank  case  immaterial. 

Disadvantages. — Cylinder  volume  and  weight  per  unit  of  power 
greater;  multiplicity  of  parts,  especially  valves,  valve  gear,  cams, 
countershaft,  etc.,  with  increased  probability  of  breakdown;  loss 
of  power  if  any  valves  are  not  gas  tight. 

The  four  cycle  engine  seems  to  lose  in  simplicity  by  comparison 
with  the  two  cycle,  but  it  is  in  far  more  common  use. 

Although  the  two  cycle  engine  receives  twice  as  many  impulses 
per  revolution  as  the  four  cycle,  it  must  not  be  concluded  from  this 
that,  for  the  same  cylinder  dimensions,  the  two  cycle  has  twice  the 
power.  In  the  four  cycle  type  the  impulse  due  to  expansion  is 
carried  throughout  nearly  the  entire  stroke,  whereas,  in  the  two 
cycle  type,  the  exhaust  valve  opens  much  earlier  and  the  impulse 
only  lasts  about  five-eighths  of  the  stroke,  as  can  be  seen  from 
Fig.  24. 

Types. 

The  internal  combustion  engine  is  commonly  called  by  a  variety 
of  names,  none  of  which  are  technically  correct  for  all  types,  for 
example,  gas  engines,  explosion  engines,  heat  engines,  etc.  Two 


TYPES,    CYCLES,    ETC.  .  41 

general  subdivisions  may  be  made,  viz.:  (1)  single  acting;  (2) 
double  acting. 

A  single  acting  engine  is  one  which  receives  the  motive  im- 
pulse on  only  one  side  of  the  piston. 

A  double  acting  engine  is  one  which  receives  the  motive  im- 
pulse alternately  on  both  sides  of  the  piston. 

All  small  high-speed  engines  are  single  acting,  and,  with  few 
exceptions,  only  large,  heavy-duty  motors  are  made  double  acting. 

A  very  common  and  unscientific  method  of  classifying  internal 
combustion  engines  depends  upon  the  fuel  consumed,  thus,  gas 
engine,  gasoline  engine,  oil  engine,  alcohol  engine,  etc.  This  is 
common  commercial  practice. 

The  only  scientific  classification  is  a  thermodynamic  one.  Heat 
is  imparted  to  the  fuel  and  medium  by  the  chemical  reaction  that 
follows  ignition.  The  method  of  applying  this  heat  to  the  work- 
ing substance  determines  the  class  in  which  the  engine  belongs. 
The  classification  is  as  follows: 

1.  Engines  receive  heat,  the  charge  being  at  constant  volume. 

2.  Engines  receive  heat,  the  charge  being  at  constant  pressure. 

3.  Engines   receive  heat,  the   charge  being   at  constant  tem- 
perature. 

Ignition  with  Charge  at  Constant  Volume. 

This  -class  of  engine  is  the  one  in  most  common  use  and  is 
frequently  erroneously  called  an  explosion  engine.  The  whole 
charge,  which  is  drawn  in  on  the  aspiration  stroke  and  com- 
pressed, is  ignited,  and,  the  charge  occupying  a  small  space,  the 
rate  of  flame  propagation  is  so  rapid  that  the  charge  practically 
burns  without  change  of  volume  before  expansion  takes  place. 
In  other  words,  combustion  is  complete  before  expansion  starts. 
The  subsequent  rapid  expansion,  with  its  accompanying  rise  of 
pressure,  furnishes  the  motive  power.  All  engines  using  gas  or 
carbureted  fuel  ignite  at  constant  volume,  and  the  Semi-Diesel 
engine  approximates  this  type. 


42  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

• 

Ignition  with  Charge  at  Constant  Pressure. 

This  principle  was  adopted  by  Brayton  in  his  engine  about 
1870.  He  apparently  got  his  idea  from  the  action  of  the  steam 
engine  to  which  its  cycle  is  analogous.  Separate  pumps  supplied 
air  and  combustible  to  the  cylinder  at  constant  pressure  and  the 
mixture  burned  as  it  entered.  The  pressure  was  therefore  con- 
stant during  the  expansion  or  combustion  stroke  until  the  admis- 
sion valve  closed.  The  increased  volume  at  constant  pressure 
drove  the  piston.  This  engine,  which  was  at  one  time  popular 
in  this  country,  is  no  longer  manufactured.  The  latest  Diesel 
engine  manufactured  in  Germany  approaches  this  principle. 

Ignition  with  Charge  at  Constant  Temperature. 

The  card  from  an  engine. built  on  this  principle  would  have  a 
combustion  line  which,  when  analyzed,  would  prove  to  be  iso- 
thermal. As  late  as  1904  the  American  Diesel  Engine  Company 
claimed  this  for  their  engine.  This  is  rather  surprising  in  view 
of  the  fact  that  isothermal  combustion  is  theoretically  the  least 
efficient.  It  would  be  possible  to  construct  an  engine  of  the 
Diesel  cycle  whereby,  air  being  previously  compressed  in  the 
cylinder  to  a  very  high  temperature,  the  fuel  could  be  injected 
during  the  combustion  stroke  at  such  a  rate  as  to  maintain  this 
temperature.  This  presupposes  a  very  accurate  and  minute  fuel 
supply  regulation. 

It  can  be  shown  mathematically  that  combustion  at  constant 
volume  gives  the  most  efficient  cycle  and  that  combustion  at  con- 
stant temperature  gives  the  least  efficient.  Combustion  at  con- 
stant pressure  gives  a  cycle  which  is  between  these  two  in 
efficiency. 

Compression. 

It  was  early  recognized  that  compression,  which  immediately 
precedes  ignition,  is  one  of  the  greatest  factors  in  internal  com- 
bustion engine  efficiency.  With  a  given  amount  of  fuel  to  be 
burned,  if  this  fuel  were  not  compressed,  the  cylinder  volume 


TYPES,    CYCLES,    ETC.  43 

would  necessarily  be  increased  by  the  ratio  of  expansion  and 
would  be  enormous  were  the  engine  non-compression.  Thus  it 
is  apparent  that  compression  is  absolutely  necessary. 

By  compressing  the  mixture  into  a  small  space  the  atoms  of 
the  fuel  are  more  intimately  mixed,  thus  aiding  combustion,  and 
they  are  brought  more  closely  together  thus  accelerating  flame 
propagation.  Compression  heats  'the  mixture,  thus  aiding  igni- 
tion and  increasing  the  initial  temperature;  it  also  greatly  in- 
creases the  mixture's  power  of  expansion. 

By  increasing  the  compression  the  necessary  clearance  or 
compression  space  is  reduced;  this  reduces  the  cylinder  wall 
area  of  radiation  and  water  jacket  length  and  as  a  direct  result 
the  loss  of  heat  by  radiation  is  diminished.  Reducing  the  clear- 
ance space  is  the  equivalent  of  increasing  the  stroke.  If  the  com- 
pression is  too  low  the  fuel  may  not  all  burn,  due  to  poor  flame 
propagation,  and  some  gases  will  not  ignite  at  all  unless  com- 
pressed to  a  certain  pressure. 

The  degree  of  compression  that  is  necessary  for  efficiency 
depends  upon  the  ignition  point  of  the  fuel,  increasing  with  this 
temperature.  There  is  a  practical  limit  to  the  degree  of  com- 
pression that  may  be  attained.  This  depends  upon  the  ignition 
temperature  of  the  fuel.  As  stated  above,  compression  increases 
the  temperature  and,  if  this  is  carried  too  far,  premature  ignition 
will  result.  The  following  compression  limits  in  pounds  are 
given  by  Lucke : 

Carbureted  gasoline,  high-speed  engine 45-95 

Carbureted  gasoline,  slow-speed,  well-cooled  engine 60-85 

Kerosene,  hot-bulb  injection  and  ignition 30-75 

Kerosene,  vaporized 45-85 

Natural  gas 75-130 

Producer  gas 100-160 

Blast-furnace  gas 120-190 


CHAPTER  V. 

CARBURETION,  THE  MIXTURE,  ITS  PREPARATION, 
CARBURETORS  AND  VAPORIZERS. 

Definitions. — Carburetion  is  the  process  of  saturating  air  or 
gas  with  a  hydrocarbon. 

The  air  or  gas  that  is  carbureted  is  called  the  medium. 

The  carburizer  is  the  agent  (fuel)  employed  to  saturate  the  air. 

A  carburetor  is  an  apparatus  used  to  charge  air  or  gas  with  a 
volatilized  hydrocarbon. 

"  The  mixture"  is  the  term  commonly  employed  to  designate 
the  product  of  the  carburetor  when  ready  for  combustion,  viz. : 
the  combination  of  fuel  and  air. 

A  "  rich"  mixture  is  one  having  an  excess  of  fuel,  and  a  "  lean" 
mixture  is  one  having  an  excess  of  air. 

A  "  charge"  is  a  cylinder  full  of  mixture. 

Carburetion. — Every  fuel  requires  a  certain  amount  of  oxygen 
for  complete  oxidation  or  combustion.  This  can  be  supplied  by 
the  atmosphere  if  suitable  means  are  at  hand  to  mix  the  air  and 
fuel.  The  various  fuels  contain  different  proportions  of  carbon, 
hydrogen  and  other  combustibles,  therefore,  will  require  propor- 
tionate amounts  of  air  to  attain  complete  combustion.  Excessive 
air  will  cool  the  mixture,  greatly  reduce  the  rate  of  flame  propa- 
gation, and  weaken  the  ignition  if  it  does  not  actually  prevent  it. 
Its  increased  volume  causes  increased  loss  of  heat  in  the  exhaust 
gases.  Too  little  air  will  result  in  incomplete  combustion,  reduc- 
ing the  efficiency  and  causing  a  carbon  deposit  in  the  cylinders. 

The  function  of  a  carburetor  or  of  a  mixing  valve  is  to  admix 
the  fuel  and  air  to  the  correct  richness,  forming  a  combustible 
gas  or  vapor.  The  rapid  advance  in  the  development  of  the 


CARBURETION.  45 

modern  internal  combustion  engine  is  due  in  large  part  to  the 
perfection  of  satisfactory  apparatus  to  carburet  air.  Successful 
working  of  such  an  engine  is  dependent  upon  the  reliability, 
certainty,  and  satisfactory  working  of  the  carbureting  device. 
Carburetion  cannot  be  carried  on  at  ordinary  temperatures  unless 
the  fuel  is  very  volatile.  For  the  less  volatile  fuels  heat  is  em- 
ployed as  an  aid,  and  in  this  case  carburetion  consists  of  atomiza- 
tion  and  subsequent  vaporization  by  heat. 

The  method  adopted  depends  upon  the  fuel  to  be  used,  there- 
fore carburetion  will  be  treated  under  the  following  five  heads : 
(1)  gas;  (2)  gasoline;  (3)  kerosene;  (4)  oil;  and  (5)  alcohol. 

1.  Gas. — Gas  must  be  prepared  for  combustion  by  intimately 
mixing  with  air.     This  may   be  accomplished  by  pumping  the 
gas  and  air  together  into  the  cylinder  or  into  the  space  outside 
the  admission  valve.     Another  method  is  to  introduce  the  gas  and 
air  into  the  cylinders  through  separate  valves. 

2.  Gasoline. — This   being  one   of   the   most    frequently  used 
fuels,  its  carburetion  will  be  treated  at  length.     It  may  be  carried 
on  by  three  distinct  methods,  the  first  two  of  which  have  prac- 
tically fallen  into  disuse. 

a.  Surface  Carburetion.- — This,  the  earliest  method  used,  con- 
sists of  evaporating  the  liquid  hydrocarbon  by  passing  a  current 
of  air  over  the  surface  of  the  liquid.     The  air  thus  becomes 
saturated  by  evaporation  of  the  liquid  from  its   free  surface. 
This   method   is  practically  obsolete   for  the   following  reason: 
Evaporation  from  the  free  surface  of  gasoline  will  tend  to  vola- 
tilize the  lighter  hydrocarbons,  leaving  a  liquid  of  rapidly  increas- 
ing density,  which  finally  loses   its  volatility  at   ordinary   tem- 
peratures. 

b.  Mechanical  Ebullition. — By   introducing   a   current   of   air 
below  the  ;surface  of  gasoline  and  allowing  it  to  bubble  to  the 
surface  a  certain  amount  of  the  liquid  is  entrained  as  mist  in  the 
air.     This  method  was  abandoned  also  for  practically  the  same 
reason  as  the  former. 

c.  Spray  Carburetion. — This  is  the  only  practical  method  now 
employed  to  convert  gasoline  into  a  combustible  vapor.     Each 


46  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

suction  stroke  of  the  piston  creates  a  vacuum  in  the  cylinder, 
which  vacuum  sucks  the  air  into  the  cylinder  through  the  mixing 
chamber  of  the  carburetor.  This  air  is  at  a  pressure  below  that 
of  the  atmosphere.  The  mixing  chamber  communicates  with  the 
gasoline  chamber  of  the  carburetor  by  a  fine  nozzle  or  needle 
valve.  As  the  air  passes  over  this  nozzle  a  spray  of  gasoline  is 
sucked  through  it  into  the  passing  air  which  it  saturates.  This  is 
made  more  clear  by  a  study  of  the  carburetor  itself. 

Carburetor  Requirements. — A  good  carburetor  or  mixing  valve 
must  fulfill  the  following  requirements:  (1)  it  must  be  adjusta- 
ble so  that  the  correct  proportion  of  fuel  and  air  is  obtained; 
(2)  this  proportion  must  be  maintained  at  varying  speeds ;  (3)  if 
possible,  the  location  of  the  spraying  nozzle  should  be  near  the 
middle  of  the  air  passage;  and  (4)  the  apparatus  must  be  simple 
and  compact. 

The  distinction  between  a  mixing  valve  and  a  carburetor  will 
be  seen  from  a  description  of  each.  In  both  cases  fuel  is  drawn 
through  a  nozzle  into  the  air  which  is  being  sucked  into  the  cylin- 
der. A  mixing  valve  has  its  nozzle  below  the  source  of  fuel 
supply  and  this  nozzle  is  opened  and  closed  by  a  valve  which  is 
lifted  at  each  aspiration  stroke  of  the  cylinder.  A  carburetor 
has  its  nozzle  just  above  the  gasoline  level  in  the  gasoline  chamber 
of  the  carburetor  and  the  fuel  is  sucked  through  the  nozzle  by 
the  air  on  each  aspiration  stroke.  In  either  case  the  flow  of 
gasoline  vapor  stops  when  the  engine  is  stopped. 

The  Schebler  Carburetor  is  one  of  the  most  popular  and  effi- 
cient of  the  high-speed  carburetors.  The  Model  D  is  shown  in 
Fig.  28.  The  opening  marked  "  gasoline  "  is  connected  to  the 
gasoline  tank  by  piping.  Gasoline  enters  at  G  and  passes  through 
float  valve  H  to  the  float  chamber  B.  The  opening  R  connects 
to  the  engine  intake  pipe,  and  A  opens  to  the  atmosphere.  When 
running,  the  engine  suction  at  R  draws  air  in  at  A,  and  as  this  air 
rushes  past  the  spraying  nozzle  D,  gasoline  is  drawn  from  B* 
through  D  and  carburets  the  air  which  passes  through  R  to  the 
engine.  The  amount  of  opening  at  D  is  regulated  'by  the  needle 
valve  £. 


CARBURETION.  4.7 

The  gasoline  in  B  is  maintained  at  a  constant  level  by  the  float 
F  as  follows :  As  the  gasoline  in  B  is  drawn  through  D  the  level 
in  the  chamber  B  falls  and  float  F  falls  with  the  gasoline  level. 
This  float,  through  a  toggle  hinged  at  /,  opens  the  float  valve  H 
admitting  gasoline  to  B.  As  the  gasoline  level  in  B  rises  it  lifts 
the  float  F  until  the  valve  H  is  closed.  This  operation  is  con- 
tinuous. 


&    AIR 


FIG.  28.— Schebler  Carburetor,  Model  D. 

The  amount  of  entering  air  is  regulated  by  the  air  valve  O. 
When  the  motor  is  running  at  its  maximum  speed,  air  is  drawn 
through  an  aperture  of  fixed  dimensions.  As  the  speed  is  in- 
creased, and  consequently  the  flow  of  gasoline  becomes  greater 
more  air  is  required  and  this  additional  air  is  supplied  by  the 
compensating  air  valve  O,  which  opens  an  amount  proportionate 
to  the  speed.  The  amount  of  air  valve  lift  is  regulated  by  the  air 
valve  adjusting  screw  M,  which  in  turn  is  locked  by  the  spring  Y 
and  lock  nut  W. 


48  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

The  quantity  of  mixture  admitted  to  the  engine  is  regulated  by 
the  throttle  disc  K,  which  is  operated  by  the  lever  P.  This  regu- 
lates the  engine  speed.  The  butterfly  disc,  shown  dotted  in  the  air 
intake,  is  used  when  starting.  Closing  this  cuts  off  most  of  the 
air  and  enriches  the  mixture.  It  is  kept  open  when  running. 

The  joint  between  the  carburetor  and  gasoline  piping  is  a 
ground  joint  with  a  reversible  union  so  that  this  joint  can  be 
broken  without  disturbing  the  carburetor  or  piping.  Joint  N  is 
made  air  tight  by  a  cork  gasket. 

The  Lunkenheimer  Mixing  Valve,  Fig.  29. — Air  entrance  is 
effected  at  1.  Gasoline  enters  at  3  through  the  needle  valve  pass- 
age 4.  The  amount  of  entering  fuel  is  .regulated  by  the  needle 
valve  which  is  operated  by  the  graduated  wheel  5.  The  mixture 
leaves  for  the  engine  at  2,  after  passing  over  the  mixing  baffle  6. 
On  jeach  aspiration  stroke  valve  7  lifts,  uncovering  the  needle 
valve  passage.  Air  is  sucked  to  the  upper  chamber,  drawing 
gasoline  from  the  needle  valve.  The  valve  is  seated  by  its  spring 
at  the  end  of  the  aspiration  stroke,  and  its  lift  is  regulated  by  the 
stop  8.  Passage  2  contains  a  throttle. 

There  are  innumerable  carburetors  and  mixing  valves  on  the 
market  and  the  above  are  chosen  as  typical  designs. 

General. — It  is  advantageous,  especially  in  cold  weather,  to 
have  the  source  of  air  supply  warmer  than  the  atmosphere.  Many 
methods  are  employed,  such  as  having  the  air  suction  drawn  from 
the  proximity  of  the  hot  exhaust  pipe,  leading  the  hot  exhaust 
gases  around  the  admission  pipe,  or  jacketing  the  carburetor  with 
the  exhaust  gases  or  heated  exhaus.t  circulating  water.  80°  F.  to 
85°  F.  is  the  best  temperature  for  admission.  The  temperature 
and  hygrometric  condition  of  the  air  supply  regulate  the  relative 
quantities  of  air  and  fuel  required  in  the  mixture.  It  will  be 
necessary  to  regulate  the  mixture .  to  meet  the  varying  atmos- 
pheric conditions. 

3.  Kerosene. — There  are  two  methods  of  treating  this  fuel : 
(a)  carburetion,  similar  to  gasoline;  and  (b)  injecting  into  the 
cylinder  or  vaporizer  near  the  air  valve,  as  in  the  case  of  the 
heavier  oils. 


CARBURETION. 


49 


a.  Carburetion  of  kerosene,  as  stated  before,  requires  the  ap- 
plication of  heat  to  aid  vaporization  at  ordinary  temperatures. 
Therefore,  the  process  consists  of  two  parts,  first  atomizing  the 
fuel  in  a  similar  manner  to  gasoline  carburetion  and  then  vapor- 


FIG.  29. — L/unkenheimer  Mixing  Valve. 

izing  this  spray  by  heating.  This  heat  is  applied  either  by  jacket- 
ing the  carburetor  or  admission  pipe,  or  by  heating  the  air  before 
passing  the  same  through  the  carburetor.  Any  well  designed 
gasoline  carburetor  with  a  hot  air  intake,  if  jacketed,  will  car- 
buret kerosene,  but  not  efficiently.  Some  kerosene  carburetors 
start  on  gasoline  and  shift  to  kerosene  after  the  engine  is  started 

4 


50  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

and  well  warmed  up.  Such  a  carburetor  is  similar  to  the  alcohol 
carburetor  shown  in  Fig.  31. 

b.  Kerosene  may  be  injected  into  the  cylinder  direct  and  the 
necessary  air  supplied  by  a  separate  valve.  Means  are  employed 
to  regulate  the  amount  of  fuel  that  is  drawn  into  the  cylinder 
each  suction  stroke.  The  passage  of  fuel  through  its  valve  atom- 
izes it,  and  upon  contact  with  the  4iot  cylinder  or  vaporizer  walls 
it  is  vaporized. 

Crossley  Vaporizer. — In  Fig.  30  the  vaporizer  is  shown  at- 
tached to  the  cylinder  head.  It  is  ribbed  to  facilitate  heating  for 


SECTION  0*  X-X 

FIG.  30. — Section  of  New  Crossley  Vaporizer  and  Valve  Chamber. 

starting  and  to  regulate  the  temperature  when  the  engine  is  run- 
ning. The  oil  sprayer  supplies  kerosene  to  the  vaporizer,  where  it 
vaporizes  on  contact  with  the  hot  vaporizer  walls.  The  heat  of 
compression  keeps  these  walls  hot  when  the  engine  is  running, 
and  near  the  highest  compression  point  the  ignition  tube  (shown 
in  section)  becomes  sufficiently  hot  to  fire  the  mixture.  The  air 
shifting  valve  permits  water  spray  to  enter  the  cylinder.  This 
regulates  the  cylinder  temperature  and  reduces  carbon  deposits. 


CARBURETION.  5! 

4.  Oil. — Heavy  oils,  those  heavier  than  kerosene,  are  generally 
sprayed  directly  into  the  cylinder.  Air  is  forced  through  a  sep- 
arate valve  into  the  cylinder  either  with  or  ahead  of  the  fuel. 
There  are  two  distinct  methods  of  vaporizing  and  igniting  heavy 
oil,  and  this  leads  to  two  types  of  engines,  the  Semi-Diesel  and 
the  Diesel.  They  are  different,  both  mechanically  and  thermody- 
namically. 

The  Semi-Diesel  Engine  compresses  the  air  to  about  85  to  215 
pounds  per  square  inch.  The  temperature  is  lower  than  the  igni- 
tion temperature  of  the  fuel.  At  the  beginning  of  the  working 
stroke  all  the  fuel  is  injected  against  a  hot  bulb  shown  in  Fig.  30, 
which  vaporizes  and  ignites  it,  practically  instantaneously.  The 
pressure  rises  to  about  260  to  350  pounds  per  square  inch.  The 
engine  approximates  the  constant  volume  type. 

The  Diesel  Engine  compresses  the  air  to  about  500  pounds  per 
square  inch.  This  gives  a  temperature  higher  than  the  ignition 
temperature  of  the  fuel.  During  the  first  part  (about  1/10)  of  the 
working  stroke,  fuel  is  injected  into  the  cylinder.  It  is  ignited  by 
the  heat  of  the  compressed  air  and  combustion  takes  place 
throughout  the  injection  period,  fuel  being  supplied  at  such  a  rate 
that  combustion  takes  place  at  approximately  constant  volume. 

Both  types  are  equipped  to  supply  scavenging  air  at  about  five 
pounds  pressure.  One  of  the  most  difficult  features  of  design 
connected  with  the  "  heavy  oil "  engines  is  to  reduce  the  deposits 
of  carbon  that  tend  to  form.  When  a  heavy  oil  is  volatilized 
there  is  a  strong  tendency  toward  chemical  change.  Its  heavy 
hydrocarbon  constituents  tend  to  decompose  into  lighter  ones. 
This  reaction,  called  "  cracking,"  which  is  absent  when  the  lighter 
fuels  are  carbureted,  leaves  a  carbon  residue.  Many  installations 
inject  small  quantities  of  steam  or  water  into  the  cylinder  during 
the  cycle  to  reduce  the  temperature  at  the  beginning  of  combus- 
tion. The  real  beneficial  result  to  be  expected  is  that  carboniza- 
tion may  be  reduced,  the  moisture  maintaining  the  carbon  in  a 
spongy  state  so  that  it  may  be  blown  out  at  the  exhaust  instead  of. 
depositing.  This  is  not  general  marine  practice,  but  is  worthy  of 


52  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

investigation.    Practically  all  large  marine  heavy  oil  engines  today 
are  Diesel  engines.    This  engine  is  described  in  Chapter  XII. 

5.  Alcohol. — Correct  carburetion  of  alcohol  is  more  difficult 
than  would  be  suspected  by  an  inexperienced  operator.  Excess  of 
air  creates  increased  loss  of  heat  through  the  exhaust  gases  and 
retards  ignition,  but  a  deficiency  of  air  causes  much  more  serious 
trouble.  The  resulting  incomplete  combustion  causes  the  forma- 


Gasoline. 


Alcohol. 


FIG.  31. — Alcohol  Carburetor. 


tion  of  corrosive  and  fouling  products  which  corrode  and  clog  the 
cylinders,  valves,  etc.  Like  kerosene,  alcohol  requires  auxiliary 
heat  for  vaporization,  although  some  few  carburetors  have  been 
built  without  provision  for  heating  the  atomized  product.  The 
heat  may  be  applied  by  any  of  the  ways  enumerated  under  kero- 
sene. The  future  form  of  carburetor  for  alcohol  seems  prob- 


CARBURETION.  53 

lematical,  but  a  likely  type  is  shown  in  Fig.  31.  This  carburetor, 
known  as  the  double  float  type,  is  constructed  to  use  either  gaso- 
line or  alcohol,  thus  permitting  the  start  to  be  made  on  gasoline 
(which  will  volatilize  cold)  and  subsequent  running  to  be  done  on 
alcohol.  Suppose  that  compartment  b  is  used  for  gasoline  and  a 
for  alcohol,  c  and  d  are  floats  in  these  chambers  that  regulate  the 
level  of  liquid  in  the  chambers  by  opening  and  closing  the  needle 
valves  g  and  h.  e  and  /  are  springs  that  can  be  used  'to  keep 
either  needle  valve  (g  or  h)  closed  when  the  other  is  in  use.  /  and 
k  are  nozzles  communicating  with  the  fuel  chambers  b  and  a.  m 
is  the  air  inlet  and  n  is  a  valve  which  can  be  rotated  so  as  to  con- 
nect the  air  inlet  m  with  the  admission  pipe.o  by  way  .of  either  / 
or  k.  o  is  the  admission  pipe  to  the  engine  and  p  is  a  throttle. 
The  carburetor  is  shown  with  both  needle  valves  closed. 

The  operation  is  as  follows :  Using  gasoline  to  start,  push 
aside  the  spring  e  allowing  the  float  c  to  operate  and  admit  gaso- 
line to  b.  With  the  valve  n  in  the  position  shown,  the  apparatus 
becomes  a  simple  float  valve  gasoline  carburetor.  Air  is  drawn 
in  through  m  over  /,  sucking  up  gasoline  vapor,  through  n  and  out 
at  o.  When  the  engine  is  warm  and  it  is  desired  to  shift  to 
alcohol,  the  spring  e  is  pushed  to  the  closed  position  and  f  is 
pushed  aside,  allowing  the  float  d  to  operate.  The  valve  n  is 
turned  so  as  to  connect  m  and  o  by  way  of  k.  We  now  have  a 
simple  float  valve  alcohol  carburetor,  the  air  being  drawn  into  m 
over  k,  sucking  up  alcohol  vapor,  and  going  out  by  way  of  n  and 
o.  This  type  of  vaporizer  is  supplied  with  preheated  air. 


CHAPTER  VI. 
IGNITION. 

Next  to  carburetion,  the  most  important  feature  in  internal 
combustion  engine  operation  is  proper  ignition.  The  abandon- 
ment of  naked  flame  ignition  because  of  its  uncertainty  leaves 
three  general  methods  of  igniting  the  compressed  mixture:  (1) 
the  electric  spark;  (2)  by  contact  of  the  mixture  with  a  heated 
tube;  (3)  by  compressing  the  charge  until  its  temperature  reaches 
the  point  of  ignition.  The  first  method,  that  of  the  electric 
spark,  is  the  one  in  most  common  use,  the  reasons  being  that  it 
has  reached  a  nearly  perfect  state  of  development  and  it  can  be 
more  easily  "  timed." 

Timing  the  spark  means  regulating1  the  point  in  the  stroke  at 
which  ignition  takes  place.  For  high-speed  engines  electrical 
ignition  is  the  only  one  flexible  enough  for  accurate  regulation. 
It  is  obvious  that  with  an  engine  running  at  600  revolutions  per 
minute,  the  stroke  being  but  1/20  second,  it  would  be  extremely 
difficult  mechanically  to  vary  to  a  nicety  the  point  in  the  stroke 
at  which  ignition  will  take  place. 

Electric  Spark. — By  shooting  a  hot  electric  spark  through  a 
compressed  charge  ignition  will  take  place.  Electrical  ignition 
may  be  subdivided  into  two  classes:  (1)  jump  spark  system;  (2) 
make  and  break  system. 

1.  Jump  Spark. — This  system  requires  among  other  things  a 
spark  plug,  which  is  shown  in  the  circuit  in  Fig.  32.  A  current  of 
high  potential  is  made  to  jump  across  a  gap  between  two  ter- 
minals of  the  spark  plug.  This  plug,  which  is  screwed  into  the 
cylinder  head,  has  its  gap  surrounded  by  the  compressed  mixture 
at  the  moment  of  ignition.  Closing  the  circuit  causes  the  spark 
to  leap  and  this  ignites  the  charge. 

A  Single  Cylinder  Ignition  Circuit  is  shown  in  Fig.  32.  The 
spark  plug  is  screwed  into  the  cylinder  head  b.  The  plug  consists 
of  a  steel  casing  a  which  screws  into  the  cylinder  head  b.  The  ter- 
minal g  is  thus  grounded  at  the  engine.  The  other  terminal  h  is 


IGNITION. 


55 


insulated  from  the  rest  of  the  plug  by  the  porcelain  collars  c  and 
d.  f  is  a  gas  tight  washer  of  asbestos.  These  collars  and  washers 
are  made  in  a  variety  of  shapes  and  of  different  materials,  but  the 
principle  is  the  same  in  all  cases. 

The  system  consists  of  two  circuits,  a  primary  and  a  secondary. 
Following  the  primary  circuit,  shown  by  the  heavy  line,  it  goes 
from  the  ground  /  through  the  battery  K  to  the  vibrator  L, 
through  the  primary  windings  of  the  induction  or  Ruhmkorif  coil 
M  to  the  terminal  N  of  the  timer.  The  timer  shaft  0  revolves,  and 
this  shaft  being  grounded,  the  circuit  is  completed  by  the  cam  on 


FIG.  32. — Single  Cylinder  Jump  Spark  Ignition,  Showing  Details  of 
Spark  Plug. 

the  shaft.  The  secondary  circuit  leads  from  the  ground  P  through 
the  secondary  winding  of  the  coil  M  to  the  terminal  r  of  the  spark 
plug,  then  down  the  spindle  ^  to  the  point  h.  The  point  g  being 
grounded,  the  circuit  is  completed  by  the  gap  between  the  two 
points  of  the  plug.  When  the  primary  circuit  is  completed  by  the 
timer,  sending  current  through  the  primary  windings  of  the  coil, 
a  high  tension  current  is  induced  in  the  secondary  windings  and 
this  current  is  strong  enough  to  overcome  the  resistance  of  the 
gap,  which  it  leaps,  t  is  a  condenser  connected  across  the  ter- 
minals of  the  vibrator.  Its  function  is  to  damp  the  break  spark 
at  L. 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


The  Induction  Coil  M  consists  of  an  iron  core  surrounded  by  a 
few  layers  of  heavy  wire,  primary  windings.  On  these,  in  turn, 
are  wound  many  turns  of  fine  wire,  secondary  windings,  wound 
in  the  opposite  direction.  All  windings  are  insulated  from  each 
other  and  from  the  core.  The  function  of  the  coil  and  vibrator 
is  to  convert  the  direct  battery  current  of  low  potential  to  cur- 
rent of  high  potential,  partaking  of  the  nature -of  a  rectified  alter- 
nating current,  for  use  at  the  plug.  The  high  tension  alternating 


From  rimer 


ill  I l 


FIG.  33.—  Wiring  for  Four  Cylinder, 
Jump  Spark  Ignition. 


To  S^ 

FIG.  34.—  Wiring  of  Coils. 


current  gives  a  hot  vibrating  spark.  The  induction  coil  must  not 
be  confused  with  the  "  spark  coil  "  described  under  "  make  and 
break  "  circuits. 

Multicylinder  ignition,  Fig.  33,  illustrates  four-cylinder  engine 
wiring.  Fig.  34  shows  the  wiring  of  the  coil.  The  timer  shaft  h 
revolves,  making  contact  with  the  terminals,  glf  gzj  gs,  g*  in  suc- 
cession. h  is  grounded  to  the  engine,  a,  b^  bz,  b3,  b^  e^  ez,  es, 


IGNITION.  57 

e4  are  plugs  on  the  outside  of  the  coil  box  and  are  connected  as 
shown  in  Fig.  34.  The  plug  a  connects  to  the  battery,  d  to  the 
ground,  elf  e2,  etc.,  to  the  spark  plugs,  and  blt  b.2,  etc.,  to  the  ter- 
minals glf  g2,  etc.,  of  the  timer.  klt  k2,  etc.,  are  the  spark  plugs. 
clt  cz,  etc.,  are  the  buzzers.  The  shaft  h  being  in  the  position 
shown,  the  primary  circuit  goes  from  ground  h,  through  g±  to  &t, 
through  vibrator  ct  and  primary  windings  of  coil  1  to  plug  a, 
thence  to  battery  and  ground..  The  secondary  circuit  1  leads  from 
ground  L  to  plug  d,  through  secondary  windings  of  coil  1,  where 
a  high  tension  current  is  induced,  to  plug  elt  thence  to  spark  plug 


FIG.  35.— Splitdorf  Timer,  Roller  Type. 

&!.  This  circuit  is  similar  to  the  one  cylinder  circuit  described 
above.  When  shaft  h  is  revolved  to  make  contact  with  g2,  the 
current  flows  through  coil  2  to  spark  plug  k2,  etc.,  and  in  this 
manner  the  cylinders  are  ignited  in  rotation. 

The  Timer. — Means  must  be  employed  with  a  multicylinder 
engine  to  ignite  each  cylinder  in  turn  at  precisely  the  proper  in- 
stant. This  is  accomplished  by  the  timer.  It  is  interposed  in  the 
primary  circuit  with  a  terminal  for  each  primary  wire  from  the 
coil,  Fig.  33. 


58  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

Fig.  35  illustrates  the  Splitdorf  timer.  The  shaft  A,  which  is 
revolved  by  gearing  from  the  cam  shaft,  is  grounded,  and  carries 
the  roller  contact  F.  The  terminals,  B,  C,  D  and  H,  are  insulated 
from  the  rest  of  the  timer.  The  primaries  for  each  cylinder  lead 
from  the  coil  to  these  terminals.  As  the  roller  F  makes  contact 
with  the  plates  G  of  each  terminal  it  completes  the  primary  circuit 
of  the  cylinder  corresponding,  firing  each  cylinder  in  turn.  The 
spark  can  be  advanced  or  retarded  by  rotating  the  collar  carrying 
the  terminals  by  means  of  a  lever  attached  to  H. 

Magnetos  and  Generators. — A  magneto  differs  from  a  dynamo 
in  that  its  magnetic  field  is  furnished  by  permanent  magnets.  A 
generator  is  in  effect  a  small  dynamo,  its  magnetic  field  being 
created  by  electromagnets.  Thus  the  magneto  is  the  lighter  and 
simpler  machine  and  is  preferable  for  some  uses.  Where  the 
machine  is  intended  for  ignition  only  the  magneto  is  generally 
used.  If  considerable  current  is  required  over  that  necessary  for 
ignition  (such  as  lighting  in  an  automobile  system),  the  genera- 
tor is  used  because  the  continual  drain  would  cause  magneto 
magnets  to  lose  their  strength.  Magnetos  are  classified  as  high 
tension  and  low  tension. 

High  Tension  Magnetos  are  used  for  jump  spark  ignition. 
They  deliver  a  high  potential  alternating  current.  To  deliver  this 
high  potential  the  armature  is  made  of  many  fine  windings  or  the 
magneto  has  a  self-contained  transformer  coil. 

An  ignition  circuit  using  the  high  tension  magneto  consists 
only  of  the  magneto  and  wiring  to  each  spark  plug.  By  means  of 
a  distributor  (similar  to  a  timer)  built  into  the  magneto,  the  high- 
potential  current  is  supplied  to  each  plug  of  the  engine  in  turn  at 
the  correct  point  of  the  cycle  for  ignition. 

Low  Tension  Magnetos  are  used  for  make  and  break  ignition. 
They  deliver  a  low  potential  direct  current  which  seldom  exceeds 
100  volts.  As  this  is  insufficient  to  leap  the  spark  gap,  a  spark  coil 
is  placed  in  the  circuit  to  increase  its  capacity.  Sometimes  this 
spark  coil  is  built  into  the  magneto  to  form  a  self-contained  igni- 
tion system. 


IGNITION. 


59 


The  Spark  Coil,  as  used  in  the  make  and  break  system,  consists 
simply  of  an  iron  core  on  which  is  wound  a  number  of  layers  of 
insulated  No.  14  copper  wire.  This  coil  is  placed  in  series  with 
the  source  of  current  supply  and  the  make  and  break  apparatus. 
The  effect,  when  the  circuit  is  broken,  is  to  cause  an  instantaneous 
and  hot  spark.  On  account  of  its  action  the  spark  coil  is  some- 
times referred  to  as  a  "  booster." 

Distributors  perform  a  similar  function  in  the  secondary  cir- 
cuit to  that  performed  by  the  timer  in  the  primary  circuit.  Fig. 
36  illustrates  a  four  cylinder  ignition  system  with  Bosch  High 


"  Primary  winding 

Secondary  winding 

_   Frame 


L  T 


Contact 
j       breaker  disc 


FIG.  36. — Four  Cylinder  Ignition,  Bosch  High  Tension  Magneto. 


Tension  Magneto,  having  a  contact  disc  or  timer  in  the  primary 
circuit  and  a  distributor  in  the  secondary.  The  armature  carries 
two  windings,  one  indicated  by  the  heavier  lines  at  the  bottom, 
called  the  primary,  the  other,  composed  of  finer  wire,  called  the 
secondary.  One  end  of  the  primary  winding  is  grounded,  the 
other  is  connected  to  the  fixed  terminal  of  the  contact  breaker 
or  timer.  This  end  is  also  joined  to  one  end  of  the  secondary 
winding  and  the  free  end  of  the  secondary  winding  is  connected 
to  the  collector  ring  carried  by  the  ebonite  spool.  When  the 
contact  points  separate,  a  current  is  induced  in  the  primary  and 


6o 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


secondary  windings  and  is  delivered  to  the  central  terminal  of  the 
distributor  disc  by  the  carbon  brush  that  bears  against  the  col- 
lector ring.  The  various  segments  of  the  distributor  are  con- 
nected to  the  spark  plugs  in  the  cylinders,  and  every  time  the 
contact  points  separate  a  spark  will  be  produced  at  one  of  the 
plugs  because  the  revolving  distributor  brush  will  be  in  contact 
with  one  of  the  distributor  segments. 

Fig.   37   illustrates   a   combined   timer  and   distributor.      The 
drive  shaft  (grounded)  carries  as  many  roller  contacts  as  there 


High  Tension 
Terminal 


Distributor 
Segment 


To  Plug 


To  Plug 


Revolving 
Member 


Hole  for 
Drive  Shaft 

FIG.  37. — Combined  Timer  and  Distributor. 

are  cylinders  to  be  fired,  these  being  spaced  properly  to  insure 
correct  timing.  One  primary  terminal  to  the  coil  is  screwed 
into  the  fiber  casing,  making  contact  with  the  rolls  and  com- 
pleting the  primary  circuit  as  the  shaft  revolves.  Secured  to  the 
drive  shaft  is  a  fiber  crown  which  carries  a  distributor  segment. 
This  is  always  in  contact  with  a  high  tension  terminal  (secondary 
terminal  from  the  coil)  in  the  distributor  head.  As  the  shaft 
revolves  the  distributor  segment  makes  contact  with  terminals  that 
connect  to  the  plugs.  This  completes  the  secondary  circuit. 


IGNITION.  6l 

2.  Make-and-Break  System. — This  system,  which  is  a  mechan- 
ico-electrical  one  requiring  cam  or  other  gearing  to  make  and 
break  a  contact  inside  the  cylinder,  is  applicable  to  slow  speed 
engines,  and  for  this  special  duty  has  some  advantages  over  the 
jump  spark.  A  moving  contact  in  the  electrical  circuit  is  mechan- 
ically made  and  broken  inside  the  cylinder.  At  the  break  a  spark 
will  leap  between  the  contacts  igniting  the  mixture.  This  system 
admits  of  two  methods:  (1)  the  wipe  spark;  (2)  the  hammer 
break.  By  the  first  method  the  contacts  are  made  to  brush 
together  and  by  the  second  the  contacts  are  brought  together 
sharply  and  separated.  The  wiring  for  both  methods,  shown  in 
Fig.  38,  is  similar.  A  small  coil  is  employed  to  step  up  the  cur- 
rent, but  no  vibrator  is  used,  as  this  would  cause  a  spark  to  occur 

Mcy/refo 

/^\ 


Grot/fret 


FIG.  38.— Circuit  for  Make  and  Break  Ignition. 

at  make  as  well  as  break,  thus  probably  igniting  the  charge  pre- 
maturely. The  circuit  shown  admits  of  battery  or  magneto  cur- 
rent. 

Wipe  Spark  mechanism  is  shown  in  Fig.  39.  The  rod  b  oscil- 
lates the  collar  a  by  means  of  a  cam  c  on  the  countershaft.  The 
collar  a  carries  the  contact  point  d,  grounded  to  the  engine.  As  the 
collar  a  oscillates  the  point  d  wipes  past  the  spring  point  e  com- 
pleting the  circuit.  The  spring  g  quickly  returns  the  collar  to  its 
original  position  when  the  cam  releases  the  rod  b,  and  the  circuit 
thus  being  broken  a  spark  will  occur  between  the  points  d  and  e. 
The  source  of  current  is  connected  to  e  by  the  terminal  /.  Ter- 
minal /  and  point  e  are  insulated  from  the  rest  of  the  mechanism. 


62 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


The  advantage  of  the  wipe  spark  over  the  hammer  break  lies  in 
the  fact  that  the  sliding  contact  prevents  carbon  deposits  on  the 
points. 

Hammer  Break. — The  principle  of  the  hammer  break  is  shown 
in  Fig.  40.  The  spindle  a,  carrying  the  contact  bf  is  actuated  by 
cam  and  rod  through  the  lever  c.  d  is  a  spring  to  keep  b  against 


FIG.  39. — Wipe  Spark  Igniter. 

the  collar.  /  is  the  cylinder  head.  Contacts  b  and  e  are  inside  the 
cylinder  and  b  is  grounded  to  the  cylinder.  Contact  e  is  insulated 
from  the  cylinder  and  its  terminal  g  is  connected  to  the  source  of 
current.  When  the  contacts  e  and  b  are  separated  mechanically, 
a  spark  occurs.  The  cam  actuating  this  gear  is  generally  situated 
on  the  countershaft  of  the  engine. 


IGNITION.  63 

Comparison  of  the  Different  Electrical  Systems. — The  make- 
and-break  system  is  the  simpler  electrically  and  less  trouble  occurs 
from  insulation  and  short  circuits  because  a  low  tension  current 
is  used  throughout.  It  is  mechanically  more  complex,  hence  is 
more  suitable  for  low-speed  engines,  and  hard  to  adapt  to  high- 
speed engines. 

Although  electrically  more  complex  than  the  make-and-break 
system,  the  jump  spark  system  has  no  moving  parts  inside  the 
cylinder,  and  its  flexibility  as  regards  spark  adjustment  makes  it 
the  universal  system  for  high-speed  engines. 


FIG.  40. — Hammer  Break. 

General. — All  contact  points  and  the  points  of  a  spark  plug 
are  made  of  a  platinum  alloy  or  other  heat  resisting  conductor. 
The  points  must  be  kept  clean  and  free  from  carbon,  as  this 
formation  tends  to  form  short  circuits  across  the  gap,  thus  damp- 
ing the  spark.  All  connections  should  be  so  arranged  that  they 
cannot  jar  loose,  and  the  insulation  must  be  protected  from  heat, 
oil,  and  especially  water. 


64 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


Dual  Ignition. — By  a  "  dual  ignition  "  system  is  meant  one  in 
which  the  current  is  supplied  from  either  a  battery  or  magneto,  or 
from  both,  at  will.  Some  systems  have  a  separate  set  of  spark 
plugs  for  each  source  of  current  supply,  and  in  this  case  the  sys- 
tem is  in  effect  two  separate  systems.  The  dual  ignition  system 
proper,  in  which  current  may  be  obtained  through  one  set  of 
plugs  from  either  battery  or  magneto,  is  shown  in  Fig.  41. 


Co// 


3$ |i.. 


TV* 

\a  c 

h  — 

Dy/> 

f> 
a/no 

FIG.  41. — Dual  Ignition  Circuit. 

F  is  a  four  way  switch  which  operates  as  follows :  Connecting 
a  and  b,  the  current  goes  from  the  dynamo  to  the  primary  of  the 
coil  direct  where  it  is  converted  to  high  tension  current.  Connect- 
ing a  and  d  the  current  goes  from  the  battery  direct  to  the  pri- 
mary of  the  coil.  Connecting  c  and  d  the  voltage  of  the  battery- 
can  be  read  by  a  volt-ammeter  in  the  circuit.  The  secondary  cir- 
cuit ^  is  similar  to  that  shown  in  Figs.  33  and  34. 

This  should  not  be  confused  with  double  ignition,  in  which 
there  are  two  separate  circuits  and  sets  of  spark  plugs,  one  for 
the  battery  and  one  for  the  magneto. 

Two-Point  Ignition. — There  is  a  tendency  in  modern  practice 
to  have  two  spark  plugs  for  each  cylinder,  so  as  to  ignite  the 


IGNITION.  65 

charge  at  two  points  nearly  simultaneously.  This  is  theoretically 
excellent,  as  it  will  accelerate  flame  propagation,  but  there  are 
several  difficulties  that  are  hard  to  overcome.  First,  the  two 
sparks  must  occur  at  correctly  timed  instants,  otherwise  the  object 
of  the  system  would  be  defeated.  Second,  if  the  two  spark  plugs 
are  situated  close  together  little  benefit  is  derived.  The  first  diffi- 
culty has  been  overcome,  and  where  design  permits  the  installa- 
tion of  two  spark  plugs  widely  separated  excellent  results  follow. 
A  large  proportion  of  aerial  motors  are  equipped  with  two-point 
ignition. 


FIG.  42.— Hot  Tube  Igniter. 

Hot  Tube  Ignition. — Although  rapidly  being  superseded  by 
electrical  systems,  the  hot  tube  is  still  being  furnished  by  some 
manufacturers.  A  typical  hot  tube  igniter  is  shown  in  Fig.  42. 
One  end  of  a  small  tube  communicates  with  the  cylinder,  the  other 
end  is  closed.  A  Bunsen  burner,  located  in  a  surrounding 
chimney,  keeps  part  of  the  tube  at  a  red  heat.  The  chimney  is 
partially  lined  with  asbestos  or  other  non-conductor,  which  re- 
duces loss  of  heat  by  radiation. 


66  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

On  the  exhaust  stroke  the  tube  is  filled  with  exhaust  gases.  On 
the  suction  stroke  part  of  these  gases  remain  in  the  tube.  On  the 
compression  stroke  the  exhaust  gases  are  compressed  into  the 
closed  end  of  the  tube  and  some  fresh  mixture  is  compressed 
into  the  cylinder  end  of  the  tube.  When  the  fresh  charge  reaches 
the  hot  part  of  the  tube  it  ignites,  and  near  the  dead  center,  when 
the  velocity  of  flame  propagation  exceeds  the  velocity  of  the  en- 
tering mixture,  explosion  takes  place.  The  point  of  ignition  may 
be  varied  by  shifting  the  chimney  along  the  tube  by  use  of  the  set 
screw  shown.  Accurate  timing  for  slow-speed  engines  is  obtained 
by  inserting  a  valve  at  the  cylinder  end  of  the  tube.  By  opening 
this  valve  at  the  correct  point  in  the  stroke  the  fresh  mixture 
comes  in  contact  with  the  hot  tube.  The  valve  is  actuated  by  cam 
gear  from  the  countershaft. 

Ignition  by  Compression. — When  a  gas  is  compressed  its  tem- 
perature rises  and  it  is  possible  to  compress  the  mixture  to  the 
point  of  ignition.  There  are  two  distinct  methods  of  applying  this 
principle. 

a.  Diesel  Method. — Air  is  compressed  in  the  cylinder  until  its 
temperature  is  far  above  the  ignition  point  of  the  fuel  and  the  fuel 
is  injected  into  this  heated  air  during  the  working  stroke. 

b.  Semi-Diesel  Method,  sometimes  called  the  hot  bulb  method, 
is  described  under  carburetion  of  heavy  oils.  Referring  to  Fig.  30, 
a  bulb  (vaporizer)  on  the  cylinder  head  is  maintained  at  ignition 
temperature  by  the  heat  of  compression.    To  start  the  engine  the 
bulb  must  be  heated  by  an  outside  flame.    When  gas  is  the  fuel, 
the  oil  sprayer  is  omitted.     Compression  is  so  regulated  that  on 
the  compression  stroke  the  velocity  of  flame  propagation  will  ex- 
ceed the  velocity  of  gases  entering  the  neck  of  the  bulb  at  the 
proper  point  in  the  stroke  for  ignition.    Timing  the  point  of  igni- 
tion is  accomplished  by  regulating  the  compression  pressure. 


CHAPTER  VII. 

COOLING    AND     LUBRICATION. 

Cooling  the  Gases. — One  of  the  measures  of  efficiency  for  an 
internal  combustion  engine  is  the  effective  utilization  of  the  avail- 
able heat  energy.  This  in  turn  depends  upon  the  initial  and  final 
temperatures  of  the  gases  that  develop  the  pressure,  if  these  gases 
be  cooled  as  far  as  possible  by  transforming  their  heat  into  work. 
Experiments  have  been  made  along  the  line  of  injecting  water 
into  the  cylinder  both  before  and  after  ignition  of  the  charge,  on 
the  theory  that  the  heat  absorbed  from  the  ignited  mixture  would 
vaporize  the  water  and  reappear  as  work  on  the  piston  in  the 
form  of  pressure  due  to  adiabatic  expansion  of  the  water  vapor. 
Although  this  reduces  the  loss  of  heat  in  the  exhaust,  it  is  open  to 
the  objection  that  it  reduces  the  net  effective  pressure.  The  prac- 
tice of  injecting  water  into  engine  cylinders  has  been  revived  in 
the  past  few  years,  it  having  been  demonstrated  that  carbon  de- 
posits are  thereby  reduced. 

Cooling  the  Cylinder.; — At  the  moment  of  ignition  the  tem- 
perature of  the  gases  rises  very  high,  sometimes  to  3,000°  F.  Due 
to  the  high  heat  developed  by  the  combustion  of  the  mixture,  it 
becomes  necessary  to  cool  the  metal  of  the  cylinder  walls,  pistons, 
valves,  etc.  Were  this  temperature  not  reduced  the  result  would 
be  leaky  valves,  deformations,  defective  alignment,  seizing  of 
piston,  and  oxidation  of  metal.  Also  it  would  be  impossible  to 
lubricate  the  cylinder  walls  because  the  lubricant  will  burn  as  fast 
as  it  is  applied  to  the  walls. 

Ordinarily  the  most  efficient  temperature  for  the  entering  mix- 
ture seems  to  be  between  80°  F.  and  85°  F.  Cooling  water  is 
generally  carried  near  the  boiling  point,  say  about  180°  F.  This  is 
sufficiently  low  to  prevent  deformation  of  the  cylinders.  There 
are  two  methods  of  cooling  the  cylinder:  (1)  water  cooling;  (2) 
air  cooling. 


68 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


Water  Cooling. — The  cylinder  is  jacketed  and  water  is  cir- 
culated through  the  jacket.  Where  unlimited  water  is  available 
the  exhaust  is  led  to  a  drain.  If  the  water  supply  is  limited  a 
tank  is  employed.  Fig.  43  illustrates  the  use  of  a  tank  and  the 
thermo-syphon  system.  The  circulating  water  enters  at  the  bot- 


L 


FIG.  43. — Thermo  Syphon  System. 

torn  of  the  jacket  and,  as  it  becomes  heated,  rises,  flowing  out  at 
the  top  to  the  tank.  A  continuous  circulation  is  thus  established. 
When  this  system  does  not  furnish  a  circulation  that  is  rapid 
enough,  a  pump  is  placed  in  the  supply  pipe  a.  For  slow  speed 
engines  this  pump  may  be  of  the  plunger  type,  if  the  water  is 
free  from  foreign  particles  such  as  dirt  and  marine  growth,  or  of 


FIG.  44. — Water  Cooling,  Radiator  and  Pump. 

the  centrifugal  type  if  the  water  is  not  clear,  as  in  marine  prac- 
tice. The  pump  is  designed  for  the  probable  working  speed  be- 
cause one  that  would  supply  sufficient  water  at  a  designed  high 
working  speed  would  be  deficient  at  low  speed,  and  one  that  was 
designed  for  a  low  speed  might  cool  the  cylinder  to  too  low  a  point 
for  efficiency  at  high  speed. 


COOLING    AND    LUBRICATION. 


69 


Fig.  44  shows  the  system  used  for  cooling  automobile  and  aero- 
plane engines,  where  a  limited  amount  of  water  can  be  carried. 
The  radiator  shown  consists  of  a  top  and  bottom  header  con- 
nected by  vertical  tubes.  These  tubes  are  covered  with  thin  fins 
to  increase  their  radiating  surface.  The  water  enters  the  cylin- 
der jacket  at  the  bottom,  flows  out  at  the  top,  heated,  and  returns 


from 
'.Ya+er  Pump 


board 


FIG.  45.— Werkspoor  Piston  Cooling  System. 

to  the  radiator  where  it  is  cooled  by  passing  through  the  tubes. 
The  circulation  is  aided  by  a  pump,  and  a  fan  circulates  the  air 
through  the  radiator  between  the  tubes.  By  reusing  the  circulat- 
ing water  it  is  "  broken/'  that  is,  the  salts  are  precipitated,  hence 
there  will  result  less  sediment  in  the  jackets. 


70  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

Cooling  valves,  pistons,  etc. — In  all  large  engines  the  heat  from 
the  piston  will  not  radiate  to  the  cylinder  walls  rapidly  enough  to 
maintain  a  safe  piston  temperature.  This  necessitates  independent 
provision  to  water  cool  the  piston.  Water  is  introduced  to  hol- 
lows cast  in  the  piston,  either  by  flexible  connections  or  by  two 
hollow  tubes  that  slide  through  a  stuffing  box  and  enter  chambers, 
one  of  which  supplies  cool  water  under  pressure  and  the  other  of 
which  receives  the  heated  discharge  water,  Fig.  45. 

Admission  valves  are  kept  cool  by  the  cool  entering  mixture, 
and  where  practical  to  let  this  cool  mixture  impinge  on  the  ex- 
haust valve  it  aids  in  maintaining  the  latter  at  a  safe  temperature. 
The  cylinder  jackets  are  carried  as  near  as  possible  to  and  around 
the  valve  seats.  Exhaust  valves  for  large  engines  are  generally 
cast  hollow  and  are  water  cooled. 


FIG.  46.— Air  Cooled  Cylinder. 

Air  Cooling. — This  system  is  not  used  as  extensively  as  water 
cooling.  A  few  automobile  and  aeroplane  engines  and  all  motor- 
cycle engines  are  air  cooled.  The  cylinder  is  cast  with  a  number 
of  fins  or  webs  on  its  outside  surface  to  increase  the  radiating 
surface.  A  fan  is  installed  to  increase  the  air  circulation  as 
shown  in  Fig.  46.  Fuel  economy  at  moderate  horse-power  and 
speed  is  better  than  in  the  water  cooled  system,  due  to  the  higher 
cylinder  temperatures,  but  as  the  engine  becomes  heated  the  de- 
veloped horse-power  falls  below  that  which  would  be  developed 
for  given  cylinder  dimensions.  As  the  cylinder  dimensions  in- 
crease it  becomes  more  difficult  to  carry  off  the  heat  fast  enough 
and  there  is  a  practical  limit  to  the  size  cylinder  that  can  be  air 
cooled.  Fig.  47  shows  the  method  of  air  cooling  the  Franklin 
automobile  motor.  Air  is  drawn  through  a  trunk  line  by  a 


COOLING    AND    LUBRICATION. 


blower  in  the  fly-wheel  casing.  The  cylinder  fins  are  vertical 
and  enclosed  in  vertical  casings  that  form  part  of  the  trunk  line; 
cooling  air  passes  from  top  to  botom  of  the  casings  along  the 
cylinder  fins. 


Cylinder  Jacket. 


Air  Inlet. 


Fl.vwITeel  Blower  Blades. 


FIG.  47. — Franklin  Air  Cooling  System. 
LUBRICATION. 

The  external  lubrication  of  an  internal  combustion  engine  pre- 
sents no  novel  features  and  requires  no  comment,  but  the  internal 
lubrication  of  the  cylinder,  piston,  etc.,  is  vital  to  the  safety  of  the 
engine.  A  steam  cylinder  lubricates  itself  by  condensation  of 
steam  on  the  cylinder  walls,  but,  due  to  the  intense  heat  in  the 
cylinder  of  an  internal  combustion  engine  and  due  to  the  high 
piston  speed,  it  is  necessary  to  have  a  film  of  oil  between  the 
piston  and  the  cylinder  walls  at  all  times. 

Kind  of  Oil. — Oils  for  lubricating  cylinders  of  internal  com- 
bustion engines  should  have  the  following  characteristics : 

First :  They  should  be  well  refined  mineral  oils ;  that  is,  they 
should  be  free  from  acid,  alkali,  tarry  matter,  suspended  matter, 
free  sulphur  and  resinous  bodies  or  bodies  which  are  removed  by 
filtering  through  animal  charcoal. 


72  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

Second:  They  should  have  sufficient  body  to  maintain  a 
lubricating  oil  film  or  seal  between  the  piston  and  the  cylinder 
walls,  thus  insuring  perfect  lubrication  of  the  pistons  and  cylinder 
walls  and  preventing  escape  of  gases  past  the  pistons  and  rings. 

Third:  The  oil  should  be  resistant  to  heat  and  oxidation  to 
such  a  degree  as  will  insure  good  lubrication  at  high  temperatures 
and  will  not  form  a  hard  carbon  deposit  in  the  cylinders. 

Fourth :  The  oil  should  not  become  solid  at  temperatures  to 
which  the  engine  is  exposed. 

In  general,  animal  and  vegetable  oils  are  not  suitable  for  the 
lubrication  of  cylinders  of  internal  combustion  engines ;  when 
exposed  to  high  heat,  they  decompose,  produce  acids  and  deposit 
excessive  carbon  in  the  combustion  chamber.  Castor  oil,  how- 
ever, is  used  to  some  extent  as  a  lubricant  for  internal  combus- 
tion engines  because  of  its  adhesive  nature,  its  property  of  keep- 
ing its  body  well  at  high  temperatures  and  its  insolubility  in  gaso- 
line. The  choice,  of  a  proper  lubricating  oil  for  an  internal  com- 
bustion engine  is  one  which  requires  considerable  study  for  each 
type  of  engine,  and  to  arrive  at  a  satisfactory  selection  it  is 
necessary  to  consider  the  bore  and  stroke  of  the  engine,  the 
materials  of  which  the  piston  and  cylinder  are  composed,  the 
clearance  between  piston  and  cylinder  walls,  the  compression  and 
speed  of  the  engine,  the  design  of  the  piston  and  the  temperature 
which  is  attained  by  the  oil  during  the  operation  of  the  engine. 

Viscosity. — The  quality  of  an  oil  that  gives  a  comparative 
measure  of  the  friction  generated  is  its  viscosity,  which  may  be 
defined  as  its  resistance  to  flow.  The  viscosity  requirements  of  an 
oil  are  influenced  by  the  tightness  of  the  piston  rings.  If  tight,  a 
light  oil  will  give  good  results.  If  badly  worn  or  loose,  a  heavy 
oil  becomes  necessary.  If  the  oil  is  too  light,  much  of  it  will  be 
drawn  past  the  piston  rings  on  the  suction  stroke.  Likewise  on 
the  compression  stroke  some  of  the  gaseous  mixture  from  the 
carburetor  will  leak  past  the  piston  rings,  and,  condensing  in  the 
crank  case,  will  tend  to  make  the  oil  still  lighter.  This  action  is 
cumulative. 


COOLING    AND    LUBRICATION.  73 

The  flash  point  of  an  oil  is  the  temperature  to  which  it  must  be 
heated  in  order  that  the  vapors  given  off  will  give  a  slight  explo- 
sion when 'a  small  flame  is  held  immediately  over  the  oil.  The 
fire  point  is  the  temperature  (approximately  50°  above  the  flash 
point)  to  which  the  oil  must  be  heated  in  order  that  it  will  take 
fire  and  continue  to  burn  when  a  flame  is  applied.  It  is  impor- 
tant that  the  flash  point  be  higher  than  the  temperature  of  the 
inner  surface  of  the  cylinder,  which  is  about  270°  F.  if  the  water 
in  the  jackets  is  at  the  boiling  point.  All  motor  oils  have  a  flash 
point  above  300°  F. 

Lubricating  oil  does  not  burn  very  easily  or  very  fast,  and  the 
time  given  for  it  to  burn  in  a  motor  cylinder  is  very  short.  At 
high  speeds  this  time  is  a  small  fraction  of  a  second.  It  would 
therefore  appear  that  a  flash  point  of  300°  F.  is  sufficiently  high 
for  almost  any  water  cooled  motor ;  it  should  be  sufficiently  high 
for  Diesel  engines  except  in  unusual  cases.  Air  cooled  motors 
might  in  some  cases  require  a  higher  flash  point. 

The  cold  point,  which  is  the  temperature  at  which  oil  freezes, 
should  be  sufficiently  low  to  insure  that  no  difficulty  will  be  en- 
countered at  the  temperatures  to  which  the  crank  case  will  be 
exposed. 

Carbon  Deposits. — Much  misinformation  has  been  published 
on  the  subject  of  carbon  deposits.  What  is  ordinarily  called 
carbon  in  cylinders  nearly  always  contains  other  matter  in  vary- 
ing quantity.  Rust  and  small  iron  particles  are  nearly  always 
present.  In  automobile  motors  a  large  percentage  of  dust  (silica) 
is  generally  present,  and  in  marine  motors  and  Diesel  engines 
salt  is  a  common  constituent. 

The  causes  of  carbon  deposits  in  cylinders  are,  briefly,  incom- 
plete combustion  of  the  fuel  and  partial  volatilization  or  decom- 
position of  the  cylinder  lubricant  to  heavier  hydrocarbons  or  even 
free  carbon.  Much  carbon  will  pass  out  with  the  exhaust,  but 
such  part  as  deposits  in  the  cylinder  will  be  hardened  under  the 
intense  cylinder  heat. 

Small  two-cycle  motors  can  be  successfully  lubricated  by  mix- 
ing lubricating  oil  with  the  gasoline  in  the  tank,  in  the  proportion 


74  INTERNAL,    COMBUSTION    ENGINE    MANUAL. 

of  about  one  pint  of  oil  to  five  gallons  of  gasoline.  In  this  method 
of  lubrication  the  oil  must  vaporize  in  the  carburetor  and  be 
carried  with  the  gasoline  vapor  into  the  cylinder  where  it  will 
condense  on  the  walls,  and,  when  choosing  an  oil  for  this,  atten- 
tion should  be  paid  to  the  characteristics  governing  its  vapori- 
zation. 

Lubricating  Systems. — Internal  combustion  engine  lubricating 
systems  may  be  divided  into  three  general  classes : 

1.  Splash  systems. — This  class  is  more  commonly  applied  to  the 
lubrication  of  internal  combustion  engines  than  any  other,  and  is 
largely  used   for  lubricating  automobile  motors.     Oil   is  main- 
tained in  the  crank  case  at  sufficient  height  for  the  crank  or  a 
small  lug  on  the  connecting  rod  to  dip  into  it  at  each  revolution 
of  the  engine,  throwing  the  oil  up  on  the  cylinder  walls,  where  the 
piston  spreads  it  evenly  over  the  surface.     Some  splash  systems 
employ  a  pump  in  addition,  to  keep  the  oil  at  a  certain  level  in 
the  crank    case  or  troughs  into  which  the  cranks  dip. 

2.  Force  feed  systems. — The  oil  is  pumped  to  all  moving  parts 
of  the  engine  under  pressure,  in  lubricating  systems  of  this  class. 
From  a  tank  in  the  base  of  the  engine,  commonly  called  the 
"  sump  tank,"   the   oil   is   pumped  through   pipes   to   the  crank 
bearings  and  thence  through  the  hollow  crank  shaft  to  the  crank 
pin  bearings.    The  cylinders  obtain  lubrication  through  the  wrist 
pins,  which  are  hollow,  and  which  receive  oil  from  a  duct  fastened 
to  the  connecting  rod.     The  lubricating  systems  of  heavy  duty 
stationary   engines,   high   speed   marine   engines,   and   aeroplane 
engines  are  generally  of  the  force  feed  type. 

3.  Mechanical  feed  systems. — The  most  general  form  of  me- 
chanical feed  employs  a  lubricator  mounted  on  the  engine  and 
operated  by  means  of  a  belt,  eccentric  or  other  driving  device. 
The  lubricator  generally  consists  of  a  series  of  small  pumps,  the 
number  depending  on  the  size  of  the  engine,  arranged  in  an  oil 
tight  tank  or  box  and  driven  by  a  common  shaft.    The  oil  is  fed 
into  ducts,  whence  it  flows  by  means  of  gravity  to  the  moving 
parts  of  the  engine.    The  rate  of  feed  is  regulated  to  about  equal 
the   rate   of   consumption,   as  none   of  the   oil   is   regained  and 


COOLING    AND    LUBRICATION. 


75 


pumped  over.     Mechanical  feed  systems  are  commonly  employed 
in  the  lubrication  of  two  cycle  marine  engines. 

The  Detroit  Mechanical  Lubricator,  shown  in  Figs.  48  and 
49,  consists  of  a  number  of  pumping  units,  all  actuated  by  the 
same  drive  shaft,  each  unit  supplying  oil  by  a  pipe  to  an  engine 
part.  Each  pumping  unit  consists  of  a  double  plunger  valveless 
pump.  The  oiler  is  driven  by  belt  or  gearing  from  the  engine, 
and  the  speed  at  which  it  pumps  is  proportionate  to  the  engine 
speed. 


FIG.  48.— Detroit  Eight  Feed  Oiler,  Belt  Drive. 


Operation,  Fig.  49. — The  upper  piston  B,  driven  through  the 
bell  crank  yoke  H  by  the  eccentric  G,  lifts  the  oil  from  the  reser- 
voir and  discharges  it  from  the  nozzle  N.  The  amount  of  oil 
discharged  is  regulated  by  the  adjusting  button  on  the  cover,  this 
button  having  at  its  lower  end  the  cam  A  which  controls  the 


76 


INTERNAL    COMBUSTION    ENGINE;    MANUAL. 


throw  of  the  piston  B.  The  lower  plunger  C  takes  the  oil  from 
the  pocket  in  the  sight  feed  chamber  under  the  nozzle  N  and 
forces  it  to  the  point  to  be  lubricated  through  the  tube  O. 

This  forcing  plunger  C  is  driven  by  the  eccentric  F  through 
the  yoke  D.  The  bell  crank  yoke  H  and  the  straight  yoke  D  give 
to  the  pistons  an  alternate  movement,  each  being  substantially  at 
rest  while  the  other  is  passing  through,  its  90°  of  most  rapid 
travel.  A  port  in  each  piston  controls  the  passages  to  the  other 
so  that  each  becomes,  without  additional  mechanism,  a  mechanic- 
ally operated  valve  for  the  other. 


FIG.  49.— Details  of  Detroit  Forced  Feed  Oiler. 


The  eccentric  G  is  driven  by  the  eccentric  F  and,  with  the 
engine  running  ahead,  is  in  the  same  position  on  the  eccentric 
shaft.  When  the  engine  is  reversed,  however,  eccentric  G  re- 
mains stationary  until  F  has  advanced  180°  in  the  opposite  direc- 
tion, where  it  is  again  picked  up  and  driven  in  the  new  direction 
by  F.  By  this  simple  method  the  passages,  ports  and  plungers  are 
made  to  automatically  and  instantly  respond  to  a  change  in  the 
direction  of  drive  without  adjustment  of  or  interruption  to  the 
flow  of  oil. 


CHAPTER  VIII. 

GOVERNING    AND     INDICATOR    CARDS. 
Governing. 

Internal  combustion  engine  governing  is  a  more  complex  propo- 
sition than  steam  engine  governing.  In  the  latter  case  the  medium 
of  power,  steam,  is  stable,  and  for  a  constant  pressure  a  given 
governor  position  will  always  give  the  same  cycle,  hence  constant 
power.  On  the  other  hand,  the  working  fluid  in  an  internal  com- 
bustion engine  is  far  from  stable.  This  medium  consists  of  the 
gas  resulting  from  the  chemical  reaction  when  fuel  and  air  are 
mixed  and  ignited  in  the  engine  cylinder.  Thus  it  is  apparent 
that  for  a  given  fuel  the  stability  of  the  internal  combustion  en- 
gine medium  depends  upon  the  accuracy  and  variability  of  mix- 
ture, degree  of  stratification  of  the  charge,  and  variations  in  igni- 
tion. The  perfection  of  agents  to  keep  these  variants  within 
reasonable  limits  has  made  possible  the  application  to  internal 
combustion  engines  of  governors  which  confine  the  speed  fluctua- 
tions to  small  limits. 

As  in  the  steam  engine,  the  governor  must  fulfill  two  essentials, 
viz. :  It  must  automatically  control  the  speed  as  far  as  possible, 
and  it  must  be  isochronal  in  the  sense  that  under  varying  loads  it 
will  make  the  engine  perform  its  cycles  in  equal  times.  • 

The  mechanical  form  of  the  governor  varies  as  in  the  steam 
engine,  being  of  such  forms  as  the  fly-ball,  inertia,  and  vibrating 
types,  etc.  The  systems  employed  are: 

1.  The  hit  and  miss  system. 

2.  Throttling  the  mixture. 

3.  Varying  the  quality  of  the  mixture. 

4.  Varying  the  point  of  ignition. 

5.  Throttling  the  exhaust. 

6.  Combination  systems. 


78  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

Governing  by  the  Hit  and  Miss  System. — In  one  of  its  forms 
this  was  the  earliest  system  employed  extensively  to  regulate  in- 
ternal combustion  engine  speed.  It  effects  this  regulation  by 
omitting  an  explosion  when  the  speed  exceeds  that  desired. 
When  running  at  the  required  speed  the  cycles  follow  each  other 
at  equal  intervals ;  if  anything  disturbs  this  equilibrium  so  as  to 
increase  the  speed  the  governor  acts  and  prevents  an  explosion 
(causes  a  "  miss  ")  on  the  following  cycle.  This  miss  reduces  the 
speed  and  the  governor  acts  in  the  opposite  direction,  causing  the 
explosions  to  recur.  The  greater  the  excess  speed,  the  greater 
will  be  the  proportion  of  "  misses  "  to  "  hits  "  until  equilibrium  is 
again  restored.  There  are  three  varieties  to  this  system : 

1.  Keeping  the  fuel  valve  closed  so  that  only  air  is  drawn  into 
the  cylinder  during  the  miss  cycle. 

2.  Keeping  the  inlet  valve  closed,  thus  preventing  admission  of 
both  air  and  fuel. 

3.  Keeping  the  exhaust  valve   open,   thus   destroying   suction 
action  on  the  admission  stroke  of  the  cycle. 

The  mechanical  operation  of  the  first  two  methods  is  the 
same,  the  only  difference  being  that  in  the  first  case  the  governor 
acts  upon  the  fuel  valve  and  in  the  second  case  it  acts  upon  the 
admission  valve.  Fig.  50,  called  the  pick-blade  governor,  illus- 
trates this  method.  A  is  the  fuel  or  admission  valve.  B  is  a  bell 
crank  lever  which  actuates  the  valve,  opening  and  shutting  it 
during  the  regular  cycle.  This  bell  crank  lever  is  in  turn  actuated 
by  the  cam  C  on  the  countershaft.  The  pick-blade  D  acts  as  the 
push  rod  between  the  valve  stem  and  the  lever  B  during  a  regular 
cycle.  This  pick-blade  is  connected  by  rod  H  and  bell  crank  F  to 
a  collar  G  on  the  governor  H.  The  governor  is  run  by  the 
main  or  countershaft  so  that  its  speed  is  proportional  to  that  of 
the  engine.  When  the  pick-blade  engages  the  valve  stem  it  is  in 
position  for  running  at  the  desired  speed.  If  this  speed  is  ex- 
ceeded, the  governor  balls  fly  outward,  raising  the  collar  G. 
This  causes  the  pick-blade  to  move  to  the  right  as  shown  and  dis- 
engage the  valve  stem  entirely.  During  the  next  cycle  and  until 


GOVERNING    AND    INDICATOR    CARDS. 


79 


the  speed  is  reduced  to  the  normal,  the  pick-bkde  does  not  engage 
the  valve  stem  and  the  valve  does  not  lift.  This  operation  causes 
misses.  When  the  speed  is  reduced  the  required  amount,  the 
balls  of  the  governor  assume  their  original  position,  the  pick- 
blade  again  engages  the  valve  stem,  and  the  original  conditions 
are  resumed. 


FIG.  50. — Pick-Blade  Governor.     Governing  by  the  "  Hit  and  Miss" 

System. 

The  system  of  governing  by  keeping  the  exhaust  valve  open  is 
often  applied  to  engines  that  have  an  automatic  spring  loaded 
admission  valve.  By  applying  the  governor  to  the  exhaust  valve 
this  can  be  kept  open  when  the  speed  exceeds  that  desired,  and 


80  INTERNAL,    COMBUSTION    ENGINE    MANUAL. 

with  this  open  no  vacuum  is  created  on  the  suction  stroke  and 
hence  no  fresh  charge  is  drawn  in.  The  result  is  a  miss  on  the 
following  cycle.  When  normal  speed  is  again  reached,  the  ex- 
haust valve  is  released  and  functions  as  originally. 

It  is  obvious  that  this  system  is  open  to  many  objections.  In  a 
four  cycle  engine  the  omission  of  a  working  cycle  will  cause  an 
appreciable  variation  of  ,the  speed  even  with  a  large  fly-wheel, 
and  if  the  load  is  suddenly  increased  just  after  the  miss  cycle, 
this  reduction  becomes  objectionably  large.  AfteV  the  idle  cycle, 
the  first  impulse  is  stronger  than  normal  due  to  the  cylinder  being 
well  scavenged  during  the  miss  cycle.  An  engine  employing  the 
hit  and  miss  system  requires  a  heavy  fly-wheel  to  produce  a  rea- 
sonably uniform  angular  velocity  in  the  crank  shaft.  This  sys- 
tem is  unsuitable  for  work  requiring  close  regulation  of  speed, 
such  as  electric  lighting,  etc.  Its  advantages  as  a  system  are  its 
mechanical  simplicity  and  its  ability  to  run  on  the  economical 
quality  of  mixture  without  variation. 

Governing  by  Throttling  the  Mixture. — A  more  efficient  sys- 
tem lof  governing  than  the  foregoing  is  that  of  throttling  the 
normal  mixture  so  that  a  smaller  quantity  of  the  charge  is  drawn 
into  the  cylinder,  but  the  proportions  of  that  charge  are  un- 
changed. The  governor  operates  the  main  throttle,  which  is 
generally  placed  in  the  admission  line  between  the  carburetor  and 
the  engine.  The  advantages  of  this  system  are  fuel  economy  and 
the  fact  that  the  engine  can  work  on  a  constant  mixture  and  re- 
ceives an  impulse  every  cycle.  The  pressure  in  the  cylinder  is 
reduced  by  throttling,  due  to  both  reduced  fuel  supply  and  to 
consequent  decreased  compression.  By  keeping  a  constant  quality 
the  danger  of  ignition  failure  is  reduced. 

When  this  system  is  used  the  engine  is  designed  for  a  very 
high  compression  at  full  power  so  that  with  a  reduced  amount  of 
fuel  the  remaining  compression  will  enable  a  good  thermal  effi- 
ciency to  be  attained.  The  advantages  of  this  system  has  caused 
a  tendency  for  its  general  adoption  for  many  uses,  wherever  the. 
variation  in  load  does  not  reduce  the  charge  below  the  limit  of 
ignition. 


GOVERNING    AND    INDICATOR    CARDS.  8 1 

Governing  by  Varying  the  Quality  of  the  Mixture. — For  a 

given  quantity  of  mixture  the  initial  pressure  obtained  will  vary 
with  the  proportion  of  fuel  and  air  in  the  mixture.  This  is  the 
principle  of  variable  quality  governing.  The  governor  may  act 
upon  the  fuel  valve,  varying  the  amount  of  fuel  per  cycle  while 
the  amount  of  air  remains  constant,  or  may  act  upon  the  air 
valve,  varying  the  amount  of  air  per  cycle,  the  fuel  valve  being 
automatic.  The  result  in  either  case  is  to  impoverish  the  mixture 
when  the  speed  exceeds  that  for  which  the  governor  is  set.  It 
has  the  advantage  that,  although  the  total  charge  of  fuel  and  air 
may  vary  in  quality,  the  quantity  admitted  each  cycle  is  constant, 
therefore  the  compression  is  the  same  for  varying  loads.  Theo- 
retically the  result  should  be  equal  thermal  efficiencies  for  all 
loads,  but  practically  the  fuel  consumption  rapidly  increases  as 
the  load  decreases. 

The  reason  for  this  decrease  of  thermal  efficiency  with  the  load 
under  this  system  of  governing  is  that  as  the  mixture  becomes 
rarer  ignition  becomes  more  difficult  and  combustion  much  slower, 
resulting  in  greater  heat  losses  to  the  cylinder  walls.  If  carried 
too  far  the  mixture  may  become  so  rare  that  it  cannot  be  ignited. 

Governing  by  Varying  the  Point  of  Ignition. — The  ignition 
systems  of  nearly  all  internal  combustion  engines  are  so  fitted  that 
the  point  in  the  engine  stroke  at  which  ignition  takes  place  may 
be  varied.  The  electrical  systems  particularly  lend  themselves  to 
this  form  of  regulation.  Thus  the  charge  may  be  ignited  before 
the  piston  reaches  the  end  of  the  compression  stroke  ("  advanced 
spark"),  at  the  end  of  the  compression  stroke  when  the  com- 
pression is  a  maximum,  or  on  the  expansion  stroke  beyond  the 
dead  center  ("retarded  spark").  It  is  evident  that  the  maxi- 
mum impulse  is  obtained  if  combustion  takes  place  when  the  com- 
pression pressure  is  a  maximum.  If  ignition  takes  place  after  the 
piston  has  passed  the  dead  center  'and  started  on  the  combustion 
stroke,  then  the  compression  being  less  than  maximum,  the  power 
obtained  is  less  than  full  power.  If  the  charge  is  ignited  and 
combustion  takes  place  before  the  piston  has  passed  the  compres- 
sion stroke  dead  center,  it  is  evident  that  the  piston  will  be  driven 
6 


82  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

backwards  ("back  fire")  unless  the  fly-wheel  inertia  is  sufficient 
to  carry  the  piston  over  the  dead  center. 

This  system  is  used  extensively  in  marine  engines  as  well  as  in 
motor  vehicles.  Its  use  facilitates  hand  starting  by  preventing 
"  back  firing."  To  start,  the  ignition  is  retarded  well  past  thel 
dead  center.  After  the  engine  is  running  the  spark  is  advanced 
until  ignition  takes  place  a  little  ahead  of  the  dead  center.  The 
reason  for  this  is  that,  combustion  not  being  instantaneous,  if  the 
charge  is  ignited  at  the  proper  point  before  the  piston  reaches  the 
dead  center,  the  maximum  pressure  of  combustion  will  occur  at 
the  end  of  the  stroke,  and  the  expansion  will  thus  be  a  maximum. 

The  proper  ignition  point  is  found  as  follows :  Advance  the 
spark  until  a  distinct  "  knock  "  is  heard.  Then  retard  the  spark 
until  this  knock  just  disappears. 

Governing  by  Throttling  the  Exhaust. — If  the  exhaust  be 
throttled  it  will  produce  a  braking  effect  or  back  pressure  during 
the  exhaust  stroke.  This  effect  is  particularly  noticeable  in  a 
single  cylinder  engine.  Another  effect  of  throttling  the  exhaust 
is  to  leave  some  of  the  products  of  combustion  in  the  cylinder 
which  prevents  a  full  charge  being  drawn  in  on  the  suction 
stroke.  Moreover,  the  reduced  charge  is  diluted  by  the  exhaust 
gases  present.  This  system  being  highly  inefficient  is  little  used. 

Combination  Systems  of  Governing. — Although  not  general, 
combination  systems  are  sometimes  used.  Some  American 
Crossley  engines  govern  by  the  variable  quantity  or  quality 
method  at  high  loads  and  by  the  hit  and  miss  system  at  low  loads. 
Some  engines  govern  by  the  variable  quantity  method  at  high 
loads  and  by  the  variable  quality  method  at  low  loads,  and  vice 
versa.  A  thermally  correct  method  is  that  advanced  by  Letombe. 
This  consists  of  increasing  the  time  of  opening  of  the  inlet  valve, 
but  decreasing  the  lift  of  the  fuel  valve  as  the  load  decreases.  In 
a  sense  this  is  quantity  regulation,  but  the  increased  opening  of  the 
inlet  valve  increases  the  total  charge,  and  thus  the  leaner  mix- 
tures are  more  highly  compressed  than  the  richer  mixtures  that 
are  used  at  the  higher  loads.  Attempts  have  been  made  to  vary 
the  compression  space  so  that  the  compression  can  be  made 
constant  for  all  loads,  but  no  practical  method  embodying  this 
principle  has  been  devised. 


GOVERNING    AND    INDICATOR    CARDS. 

Indicator  Cards. 

The  theoretical  four  cycle  engine  indicator  card  with  variations 
is  shown  in  Figs.  51  to  56.  Fig.  51  illustrates  a  theoretically 
perfect  card.  All  the  strokes  and  events  in  the  cycle  are  marked, 


FIG.  51. — Normal  Indicator  Card. 

and  starting  at  any  point  the  cycle  can  be  easily  traced.  It  is  ap- 
parent when  tracing  the  cycle  that  the  lower  loop  is  traced  in  the 
opposite  direction  to  the  upper  loop.  This  indicates  a  loss  of 


FIG.  52.— Effect  of  Throttling  the  Normal  Charge. 

work  and  the  work  represented  by  the  lower  loop  must  be  sub- 
tracted frorrf  that  represented  by  the  upper  loop  to  get  the  net 
work  of  the  cycle.  In  cards  52  to  54  the  suction  and  exhaust 
strokes  are  omitted  for  simplicity  of  discussion. 


84 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


Throttling. — Fig.  52  shows  the  effect  of  throttling  the  normal 
charge.  A  number  of  cards  are  superposed  to  illustrate  the  point 
that  as  the  charge  is  throttled  the  card  becomes  smaller,  showing  a 
decrease  in  total  work.  Throttling  decreases  the  amount  of  mix- 
ture that  is  drawn  in  each  cycle.  As  the  charge  is  reduced,  the 


FIG.  53. — Effect  of  Retarding  Ignition. 

compression  space  being  the  same,  the  compression  pressure  is 
lowered,  and  as  a  direct  result  of  the  reduced  pressure  combus- 
tion is  slower.  These  points  are  indicated  in  the  card  by  the 
lowered  compression  line  and  the  sloping  combustion  line,  re- 
spectively. 


FIG.  54. — Ignition  Too  Early. 

Retarded  Ignition. — Several  cards  are  superposed  in  Fig.  53 
to  show  the  effect  of  retarding  the  ignition.  If  ignition  takes 
place  after  the  piston  passes  the  dead  center  this  is  indicated  on 
the  card  by  the  combustion  line  returning  along  the  compression 
line  until  the  point  of  ignition  is  reached.  The  later  the  ignition 
the  lower  will  be  the  compression  at  the  point  of  ignition,  there- 
fore the  combustion  will  be  slower  and  the  combustion  line  will 
be  lower. 


GOVERNING    AND    INDICATOR    CARDS.  85 

Advanced  Ignition. — Fig.  54  is  a  card  from  an  engine  that  has 
the  spark  advanced  too  far;'  in  other  words,  the  ignition  is  too 
early.  Ignition  in  this  case  takes  place  before  the  end  of  the 
compression  stroke,  the  maximum  pressure  is  attained  before  this 
stroke  is  completed,  and  the  result  is  a  loop  in  the  upper  part  of 
the  card,  which  loop  being  traced  in  the  reverse  direction  to  the 
general  direction  of  the  cycle  represents  a  loss  of  work. 

Faulty  Exhaust. — Fig.  55  is  a  card  taken  from  an  engine  with 
a  faulty  exhaust.  This  fault  may  arise  from  a  clogged  exhaust, 
the  exhaust  valve  or  passages  may  be  designed  too  small,  the  ex- 
haust valve  may  be  incorrectly  timed,  the  exhaust  passage  may 


FIG.  55'.— Faulty  Exhaust. 

be  so  long  as  to  create  a  back  pressure  or  may  have  sharp  bends 
in  it.  Any  cause  that  would  interrupt  the  exhaust  enough  to 
create  a  back  pressure  will  be  indicated  on  the  card  by  a  rise  in 
the  exhaust  line. 

Faulty  Admission. — When  the  suction  line  falls  below  the  at- 
mospheric as  in  Fig.  56,  this  indicates  that  the  admission  is  partly 
choked.  This  may  be  caused  by  too  small  an  admission  valve, 
admission  passages  too  small  or  too  many  bends  in  the  passage, 
inlet  choked,  or  not  enough  lift  to  admission  valve;  if  a  spring 
loaded  admission  valve  then  the  spring  ma'y  be  too  strong,  -thus, 
decreasing  the  lift. 


86 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


Fig.  57  is  an  indicator  card  from  a  two  cycle  engine,  the  upper 
card  being  taken  from  the  cylinder  of  the  engine  and  the  lower 
card  from  the  crank  case  or  compressor.  These  are  traced  in 
opposite  directions  so  that  the  work  indicated  is  the  difference 
between  the  works  represented  by  the  two  cards.  The  upper 
card  is  traced  in  the  forward  direction. 

From  the  foregoing  examples  it  can  be  readily  seen  how  impor- 
tant is  the  information  that  can  be  gained  from  good  indicator 
cards.  All  faults  of  internal  working  may  be  obtained  from  well 
taken  cards.  They  give  data  on  performance,  and  valve  settings, 
etc.,  can  be  checked  by  them.  Manufacturers,  however,  are  more 


,          FIG.  56. — Faulty  Admission  or  Suction. 

interested  in  the  brake  horse-power  than  in  the  indicated  horse- 
power, and  all  factory  tests  are  made  for  the  former  by  means 
of  a  dynamometer. 

Indicators.  The  Manograph. — The  power  of  an  internal 
combustion  engine  may  be  measured  in  a  manner  similar  to  that 
employed  in  measuring  the  power  of  a  steam  engine.  That  is, 
indicator  cards  are  taken  to  obtain  the  mean  effective  pressure 
acting,  and  this,  with  the  number  of  revolutions  and  the  engine 
dimensions,  gives  the  necessary  data  for  use  in  the  horse-power 
formula.  For  slow  moving,  heavy  duty  engines,  indicators  simi- 
lar to  steam  engine  indicators  may  be  used.  These  indicators 


GOVERNING    AND    INDICATOR    CARDS.  87 

have  external  springs.  However,  they  arc  impractical  for  high- 
speed engines  because  of  the  inertia  of  the  parts,  the  liability  of  the 
cords  and  other  flexible  parts  to  stretch,  and  the  frequency  with 
which  the  springs  break.  Indicator  cards  for  high-speed  engines 
are  taken  by  an  ingenious  device  called  the  manograph.  This 
indicator  overcomes  the  inherent  difficulties  of  the  ordinary  piston 


Exhaust  00e#s. 


Case  Card. 

FIG.  57.— Two  Cycle  Engine  Card. 

type  of  indicator  by  substituting  a  beam  of  light  for  the  pencil  of 
the  ordinary  indicator,  and  this  beam  traces  a  card  on  a  ground 
glass  screen  or  a  photographic  plate.  The  former  is  used  for  a 
casual  inspection  of  the  engine's  performance  and  the  latter  is 
used  when  a  permanent  record  is  desired. 


88 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


FIG.  58.— The  Manograph,  Cross  Section. 

The  manograph,  which  can  be  seen  in  the  Naval  Academy 
laboratory  on  the  Mietz  and  Weiss  engines,  consists  of  a  light- 
tight  box  mounted  on  a  tripod.  At  one  end  of  this  box,  Figs.  58 
and  59,  a  mirror  N  is  so  mounted  that  it  is  capable  of  rotation 
about  two  axes  at  right  angles  to  each  other.  An  acetylene 
burner  G  on  one  side  of  the  box,  shining  through  a  diaphragm, 
reflects  a  beam  of  light  through  the  prism  H  to  the  mirror  N. 


FIG.  59.— Details  of  Manograph. 


GOVERNING    AND    INDICATOR    CARDS.  89 

This  beam  is  again  reflected  from  the  mirror  N  on  to  the  screen 
or  plate  D.  The  mirror  N  is  given  two  motions,  one  in  proportion 
to  the  piston  motion  and  the  other  at  right  angles  to  the  first  in 
proportion  to  the  pressure  on  the  piston  at  any  simultaneous 
piston  position.  As  the  mirror  moves  in  two  directions  the  beam 
of  light  will  follow  a  path  which  is  compounded  from  two  rec- 
tangular co-ordinates,  one  proportional  to  the  piston  position  and 
the  other  proportional  to  the  simultaneous  piston  pressure.  In 
other  words,  the  beam  will  trace  a  card  on  the  screen  similar  to  a 
card  obtained  by  an  ordinary  indicator,  but,  since  the  moving  part 
in  the  manograph  is  the  beam  of  light  which  has  no  inertia,  the 
inaccuracies,  due  to  inertia  of  parts,  etc.,  are  eliminated. 


FIG.  60. — The  Manograph. 

Motion  proportional  to  pressure  is  given  the  oscillating  mirror 
as  follows :  The  mirror  is  mounted  on  springs,  Fig.  59,  which 
tend  to  keep  it  parallel  to  the  screen.  The  tube  T  communicates 
with  the  engine  cylinder  and  allows  the  cylinder  pressure  to  act 
on  the  diaphragm  M.  This  diaphragm  is  connected  with  the 
mirror  TV  by  a  pin  offset  from  the  mirror  center.  It  is  obvious 
that  the  mirror  will  be  rotated  by  this  pin  an  amount  proportional 
to  the  pressure  on  the  diaphragm,  which  is  the  cylinder  pressure. 
The  tube  T  can  communicate  with  the  different  cylinders  on  a 
multicylinder  engine  by  means  of  a  multiway  cock. 


90  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

Motion  proportional  to  the  piston  travel  is  given  the  mirror  N 
as  follows:  the  flexible  shaft  R  (Fig.  60)  connects  the  crank 
shaft  center  to  L  and  rotates  with  the  shaft.  By  means  of  the 
gear  L  and  a  pin,  which  is  90°  on  the  mirror  from  the  other  pin, 
motion  proportional  to  the  piston  travel  is  imparted  to  the  mirror, 
for  the  mirror  receives  one  complete  oscillation  each  revolution  of 
the  engine. 

The  angular  motion  of  the  mirror  is  very  small.  The  thumb 
screw  F  is  for  the  purpose  of  establishing  synchronism  between 
the  engine  crank  and  the  small  manograph  crank  that  actuates 
the  pin  c. 


FIG.  61. — Prony  Brake. 

.  Dynamometers  are  used  for  measuring  the  brake  horse-power 
of  engines.  This  instrument  takes  a  variety  of  forms,  the  com- 
monest of  which  is  the  Prony  Brake.  It  is  shown  in  its  typical 
form  in  Fig.  61.  //is  the  fly-wheel  of  the  engine,  turning4  as  in- 
dicated by  the  arrow.  The  lever  A  rests  on  the  wheel  H  as  shown. 
K  and  L  are  wooden  blocks,  which  are  pressed  against  the  face  of 
the  fly-wheel  by  the  tension  produced  by  the  adjustable  strap  B 
and  the  weight  of  the  yoke  O ,  thus  applying  a  friction  load  to  the 
fly-wheel  as  desired.  The  pressure  due  to  the  energy  absorbed  by 
the  brake  is  carried  by  the  lever  A  and  post  P  to  the  platform 
scales  S,  which  are  adjusted  to  just  balance  the  load. 


GOVERNING    AND    INDICATOR    CARDS.  9 1 

If  R  =  Length  of  the  brake  arm  or  lever  R  in  feet. 
N=  Revolutions  per  minute  of  the  fly-wheel. 
W  =z  Weight  in  pounds  at  distance  R}  measured  by  scales. 

27rRNW 


Then  the  brake  horse-power  would  be 


33,000 


The  value  — - —  is  called  the  brake  constant,  and,  for  the  same 
33,000 ' 

brake,  is  the  same  for  all  loads. 

Before  starting  a  test  a  zero  reading  of  the  brake  is  obtained, 
since  the  scales  weigh  not  only  the  pressure  due  to  the  friction 
load  on  the  lever,  but  also  the  weights  of  the  brake  and  post  P. 
To  determine  the  zero  reading,  the  strap  B  is  loosened  and  the 
fly-wheel  is  turned  by  hand  in  one  direction  and  the  scale  weight  is 
noted.  Then  the  fly-wheel  is  turned  in  the  opposite  direction  and 
the  scale  weight  is  again  noted.  The  friction  between  the 
loosened  brake  band  and  the  fly-wheel  is  assumed  the  same  for 
both  directions  of  rotation.  By  adding  these  two  weight  read- 
ings together  and  dividing  the  result  by  two,  the  mean  weight  of 
that  part  of  the  brake  that  rests  on  the  scales  is  determined.  This 
is  the  zero  reading. 


CHAPTER  IX. 
OPERATION,    TROUBLES,    AND    REMEDIES. 

To  Start  and  Stop  a  Motor. — Small  motors  may  be  started  by 
hand  by  giving  a  few  turns  to  the  fly-wheel  or  to  a  crank  fitted  to 
the  crank  shaft,  but  the  larger  engines  require  an  auxiliary  start- 
ing mechanism.  Some  engines  are  fitted  so  that  they  may  be  run 
by  compressed  air  for  a  few  revolutions  until  the  first  explosion 
is  obtained.  Another  method  is  to  introduce  a  charge  of  mixture 
into  a  cylinder  by  a  pump,  and  then  to  fire  this  charge  by  the 
igniter  or  a  detonator.  With  this  latter  method,  care  must  be 
taken  that  the  piston  is  on  the  expansion  stroke,  for,  if  it  is  on 
the  compression  stroke,  a  back-fire  will  result  and  the  engine  will 
start  in  the  reverse  direction ;  this  causes  undue  stress  on  the  parts 
and  may  even  fracture  the  main  or  crank  shaft. 

In  most  engines  the  point  of  ignition  is  capable  of  adjustment. 
In  this  case  retard  the  spark  so  that  ignition  will  occur  after  the 
crank  passes  the  dead  center.  See  that  the  ignition  circuit,  oiling 
gear  and  cooling  water  are  in  order  and  turned  on.  Open  the 
throttle,  fuel  valve  to  carburetor  if  installed,  prime  the  cylinder 
and  open  the  relief  cocks  on  the  cylinders,  if  necessary.  Give  the 
engine  a  few  turns  by  the  fly-wheel,  if  small,  or  the  starting  de- 
vice, if  large,  and,  if  everything  is  in  order,  the  engine  will  start. 
Opening  the  relief  cocks  relieves  the  compression  and  makes 
cranking  easy;  on  the  other  hand,  relieving  the  compression 
makes  ignition  more  difficult.  The  behavior  of  the  engine  at  hand 
will  govern  this  point.  After  the  engine  is  started,  adjust  the 
ignition  to  the  proper  lead,  close  the  relief  cocks  if  open,  see  that 
the  oil  and  water  are  working  properly,  and  adjust  the  mixture  if 
necessary.  These  general  instructions  may  be  modified  for  dif- 
ferent types  of  engines.  If  an  engine  is  to  stop  but  a  few  mo- 
ments, the  ignition  circuit  may  be  broken,  if  of  the  jump  spark 


OPERATION,    TROUBLES,    AND    REMEDIES.  93 

type  with  battery  and  coil.  The  few  revolutions  due  to  inertia 
after  the  spark  is  cut  off  will  leave  the  cylinders  charged  with  the 
mixture.  By  again  closing  the  ignition  circuit  a  spark  will  jump 
in  the  cylinder  that  has  its  piston  in  the  firnig  position,  and,  if  the 
mixture  is  still  in  combustible  form,  the  engine  will  start  without 
cranking.  This  is  called  "  starting  on  spark." 

To  stop  the  engine,  close  the  throttle,  break  the  ignition  circuit, 
and  close  the  fuel  valve.  If  exposed  to  freezing  weather,  drain 
engine  jackets  and  connecting  pipes.  Although  it  has  been  rec- 
ommended that  the  oil  supply  be  shut  off  before  the  engine  is 
stopped  in  order  that  the  surplus  oil  may  be  carried  out  with  the 
exhaust,  the  author  is  not  in  agreement.  If  the  oil  supply  is 
properly  regulated,  there  will  not  be  enough  surplus  to  cause 
serious  clogging  in  the  cylinder  or  valves,  whereas  the  serious  re- 
sults that  might  occur  if  the  engine  were  started  without  turning 
on  the  oil  supply  (as  might  easily  happen  if  other  than  the  regular 
hand  started  the  engine)  are  obvious.  Wrecks  from  this  cause 
are  not  infrequent.  In  modern  practice,  especially  where  the 
splash  system  is  used,  the  oil  supply  is  left  turned  on  at  all  times. 
This  does  not  apply  to  heavy-duty  motors  having  special  feed 
systems. 

Failure  to  Start. — Should  the  motor  fail  to  start,  the  trouble 
can  only  be  found  by  a  man  conversant  with  the  interrelation  of 
the  parts  of  the  machine  and  their  relative  functions,  and  "  trouble 
hunting  "  resolves  itself  into  an  investigation  of  the  different  in- 
tegral systems  of  the  motor.  Of  course  many  causes  of  non- 
starting  are  apparent  from  the  behavior  of  the  machine,  and  an 
experienced  hand  will  generally  have  little  trouble  in  finding  the 
defect.  However,  occasionally  a  defect  will  baffle  even  an  expert 
until  he  has  thoroughly  overhauled  and  analyzed  the  motor. 

When  investigating  non-starting,  divide  the  machine  as  follows : 

1.  Ignition  system. 

2.  Fuel  system. 


94  INTERNAL    COMBUSTION    ENGINfc    MANUAL. 

Non-Starting  Due  to  Faulty  Ignition. 

First  look  to  the  spark.  It  may  be  too  feeble  to  ignite  the 
mixture  or  may  not  occur  at  all.  In  this  case  first  test  the  battery. 
If  this  is  found  in  good  condition,  test  the  line  up  to  the  plug 
for  broken  wires,  short  circuits  or  poor  contacts.  Finally  look  at 
the  plug.  It  may  be  too  foul  for  the  spark  to  bridge,  the  points 
may  be  too  far  apart,  or  the  insulation  may  be  defective. 

If  a  good  spark  is  present  at  the  plug,  then  it  may  be  taking 
place  at  the  wrong  part  of  the  cycle,  due  to  the  timer  being  out  of 
adjustment.  This  discrepancy  is  made  good  by  so  adjusting  the 
tinier  that  the  spark  will  occur  at  or  just  beyond  the  end  of  the 
compression  stroke.  If  the  spark  is  strong  enough  for  ignition 
and  is  properly  timed,  then  the  trouble  will  be  found  under  the 
second  head. 

Non-Starting  Due  to  Fuel  Supply. 

The  tank  may  be  empty  or  the  fuel  valve  closed.  Although 
this  sounds  childish,  many  operators  have  wasted  much  valuable 
time  trying  to  start  under  these  conditions.  The  feed  pipe  may 
be  clogged.  Often  waste  or  other  foreign  matter  find  their  way 
into  the  feed  pipes  through  the  tank.  The  throttle  or  the  air  valve 
may  be  stuck.  Defective  adjustment  of  the  air  valve  may  result 
in  a  non-combustible  mixture.  The  carburetor  may  be  out  of 
order.  A  leaky  needle  valve,  resulting  in  a  flooded  carburetor,  is 
a  frequent  source  of  trouble.  The  compression  may  be  defective, 
due  to  leaky  or  broken  piston  rings  or  valves.  This  is  evidenced 
by  the  small  resistance  encountered  when  cranking  the  engine.  A 
broken  valve  stem  or  loose  valve  cam,  which  does  not  show  at 
once,  may  cause  a  valve  to  become  inoperative.  In  a  new  in- 
stallation the  tank  may  be  too  low  to  supply  a  gravity  feed,  or  the 
lead  of  feed  pipe  may  be  bad. 

Common  Troubles  and  their  Causes. 

Back-Firing. — This,  one  of  the  commonest  of  troubles,  con- 
sists of  explosions  in  the  passages  outside  of  the  cylinder.  They 


OPERATION,    TROUBLES,    AND    REMEDIES.  95 

may  be  located  in  the  exhaust  pipe  or  passages,  or  in  the  inlet 
passage  between  the  carburetor  and  inlet  valve.  In  the  case  of 
exhaust-passage  explosions,  the  ignition  may  be  too  late.  Com- 
bustion is  incomplete  when  the  exhaust  valve  opens,  and  some  of 
the  unburnt  charge  finds  its  way  to  the  exhaust  passage,  where  it 
explodes.  When  governing  by  the  hit  and  miss  system  the 
charge  of  a  miss  cycle  may  explode  in  the  exhaust  passage  when 
the  hot  exhaust  of  the  next  exploded  charge  comes  in  contact 
with  it.  A  mixture  which  burns  so  slowly  that  combustion  is  in- 
complete when  the  exhaust  valve  opens  will  have  the  same  effect 
as  late  ignition. 

Back-firing  in  the  admission  passage  is  more  perplexing.  A 
leaky,  broken  or  badly  timed  admission  valve  may  transmit  the 
combustion  within  the  cylinder  to  the  fresh  charge  in  the  admis- 
sion passage,  causing  a  back-fire  there.  Another,  and  very  com- 
mon, cause  for  this  form  of  back-firing  is  a  too  thin  mixture.  A 
very  lean  mixture  burns  slowly,  and  the  combustion  may  continue 
throughout  the  exhaust  stroke  until  the  inlet  valve  opens,  thus 
exploding  the  mixture  in  the  inlet  passage.  A  very  rich  mixture 
might  act  in  the  same  manner,  but  it  is  more  likely  to  cause  a 
back-fire  in  the  exhaust  passage.  A  loose  valve  cam  may  cause 
back-firing  by  timing  an  admission  or  exhaust  valve  improperly. 

Misfiring. — There  are  two  distinct  classes  of  misfiring,  con- 
tinuous and  intermittent.  Continuous  misfiring  of  one  cylinder 
of  a  multiple  cylinder  engine  is  a  simple  problem.  The  trouble  is 
almost  certain  to  be  in  the  ignition  system,  because  the  operation 
of  the  other  cylinders  indicates  that  the  fuel  supply  is  operative 
as  far  as  the  admission  valve  of  the  defective  cylinder,  and  were 
trouble  located  in  the  valves  of  the  defective  cylinder  it  would 
generally  be  accompanied  by  back-firing.  If  the  valves  are  found 
to  be  functioning  correctly  then  the  ignition  system  must  be  over- 
hauled. The  system  must  be  operative  as  far  as  the  coil  because 
if  it  were  defective  in  the  battery  or  primary  line  to  the  coil  all 
the  cylinders  would  fail  to  fire.  Among  the  ignition  defects  that 
might  cause  misfiring  in  one  cylinder  are  foul  or  defective  plug, 


96  INTERNAL    COMBUSTION    ENGINE;    MANUAL. 

broken  wire  or  bad  contacts,  or  improperly  adjusted  coil  vibrator. 
These  are  all  easily  found  by  simple  electrical  tests. 

Intermittent  misfiring  may  be  caused  by  improper  mixture, 
weak  battery,  poorly  adjusted  coil,  broken  wires  or  connections 
that  are  in  contact  intermittently  due  to  the  vibration  of  the  en- 
gine, dirty  sparking  device,  admission  valve,  if  automatic,  not 
working  freely,  exhaust  valve  not  closing  every  cycle,  leaky  valves 
and  poor  compression,  or  water  in  the  gasoline. 

Carburetor  explosions  have  the  same  origin  as  admission  pipe 
back-firing. 

Muffler  explosions  have  the  same  origin  as  exhaust  pipe  back- 
firing. 

Weak  explosions  are  due  to  late  ignition,  weak  battery,  poor 
quality  of  the  mixture,  insufficient  compression,  or  loss  of  com- 
pression due  to  leaky  or  broken  piston  rings  or  valves.  Over- 
heating may  give  weak  explosions  and  attendant  loss  of  power  due 
to  the  dissociation  of  the  mixture  to  its  elements. 

Overheating  may  be  occasioned  by  one  of  three  causes,  excess 
friction  due  to  poor  adjustment  of  bearings,  etc.,  defective  cir- 
culating water  supply,  or  failure  of  the  lubricating  system.  The 
water  supply  may  fail  totally  or  partially  due  to  pump  break- 
down, clogging  of  the  pipes,  closed  valve  in  the  line,  or  sediment 
on  the  cylinder  walls.  When  the  water  supply  fails  the  tempera- 
ture quickly  rises  high  enough  to  burn  the  oil  and  damage  ensues, 
the  piston  rings  and  cylinder  walls  wear  and  the  piston  will  ulti- 
mately seize.  Failure  of  the  oil  supply  if  not  discovered  early  re- 
sults in  the  same  serious  trouble.  Serious  overheating  is  at- 
tended by  loss  of  power  and  this  is  an  early  indication  that  should 
be  a  warning  signal  to  an  experienced  man.  Sharp  clicking,  simi- 
lar to  a  spark  knock,  may  be  the  first  symptom. 

Knocking  may  be  due  to  mechanical  trouble  such  as  loose  bear- 
ings, etc.,  or  to  explosive  defects.  Under  the  latter  head  there  are 
two  recognized  classes  of  knocks,  "  gas  knocks "  and  "  spark 
knocks."  A  gas  knock  is  caused  by  too  rich  a  mixture  or  by 
opening  the  throttle  too  quickly.  It  is  an  infrequent  phenomenon. 
A  spark  knock  is  caused  by  advancing  the  spark  too  far.  A 


OPERATION,    TROUBLES,    AND    REMEDIES.  97 

slight  pre-ignition  occurs,  and  though  it  is  not  early  enough  to 
cause  reversal  of  the  engine  rotation,  it  puts  undue  stress  on  the 
parts  and  causes  a  tinny  thump.  Carbon  deposits  will  cause 
knocking  in  the  cylinder.  Near  the  end  of  the  compression 
stroke  these  become  incandescent  and  premature  ignition  results. 

Crank  case  explosions  in  a  two  cycle  engine  are  caused  by  a 
thin  mixture  or  a  retarded  spark.  In  either  case  combustion  is 
not  complete  when  the  admission  port  is  uncovered  and  the 
burning  gases  come  in  contact  with  and  ignite  the  fresh  charge  in 
the  admission  pipe.  The  explosion  transmitted  through  this  pipe 
to  the  crank  chamber  may  be  a  source  of  much  annoyance,  for 
frequently  the  crank  case  cover  gasket  is  blown  out  and  must  be 
replaced  to  keep  the  case  gas  tight. 

A  smoky  exhaust  indicates  too  rich  a  mixture  or  an  excess  of 
lubricating  oil.  In  the  latter  case  the  exhaust  is  black  or  dark 
brown,  burnt  oil  vapor  being  present.  In  the  former  case  the 
exhaust  is  generally  hazy  and  lighter  and  carries  the  pungent 
smell  of  unburnt  fuel. 

Lost  compression  may  be  due  to  improper  lubrication.  An 
important  point  that  is  often  overlooked  is  that  the  film  of  oil 
between  the  piston  ring  and  cylinder  forms  a  packing,  and,  if  this 
is  not  perfect,  the  gas  will  leak  by  on  the  compression  stroke. 
This  is  technically  known  as  "blowing."  Other  and  more  fre- 
quent causes  of  loss  of  compression  are  overheating,  leaky  or 
broken  valves  or  rings,  leaky  spark  plug  gaskets  and  relief  cocks, 
and  scored  or  worn  cylinder  walls. 

Premature  ignition  may  be  produced  by  advancing  the  spark 
too  far,  too  high  compression,  overheating,  overloading  the  engine, 
or  by  carbon  deposits  on  the  piston  or  cylinder  heads  becoming 
incandescent.  The  remedies  are  obvious.  Carbon  deposits  must 
be  removed  periodically.  This  is  generally  done  by  scraping, 
although  there  are  several  reliable  solutions  on  the  market  for 
this  purpose. 

Carburetor  troubles  are  common  and  numerous.  The  needle 
valve  may  leak  and  flood  the  gasoline  chamber.  This  will  cause  a 
very  rich  mixture,  and  can  be  remedied  by  grinding  the  valve. 

7 


98  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

The  air  valve  or  throttle  may  become  stuck.  The  auxiliary  air 
valve  spring  may  not  be  properly  adjusted  to  give  the  correct 
mixture  at  high  speeds.  Water  may  accumulate  in  the  float 
chamber,  if  present  in  the  gasoline.  A  drain  cock  is  generally 
provided  to  avoid  this  difficulty.  The  spray  nozzle  may  clog  if 
there  is  dirt  in  the  gasoline.  Gasoline  should  be  thoroughly 
strained  through  chamois  before  putting  it  into  the  tank.  This 
will  remove  all  dirt  and  water,  if  carefully  done.  A  thorough 
knowledge  of  the  carburetor  is  essential  for  successful  operation 
of  any  internal  combustion  engine. 

General. 

Pressure  Diagram. — The  diagrams  in  Fig.  62  show  the  effect 
of  multiplying  the  cylinders  of  an  engine.  They  are  constructed 
by  superposing  the  cards  of  a  one  cylinder  engine  in  the  appro- 
priate phase  of  two  successive  cycles.  Similar  diagrams  can  be 
made  for  two  cycle  engines.  The  upper  line,  which  represents  the 
pressure  acting  during  two  complete  cycles,  shows  1,080°  or  six 
strokes  of  idle  effort  during  two  cycles.  The  second-  line,  which 
represents  a  two  cylinder  engine,  shows  that  pressure  is  acting  50 
per  cent  of  the  time.  It  is  not  until  we  compound  to  six  cylinders 
that  we  obtain  an  overlapping  pressure. 

Long  and  Short  Stroke  Motors. — The  proportion  of  cylinder 
diameter  ("bore")  to  stroke  is  a  problem  that  has  caused  more 
discussion  and  resulted  in  less  uniformity  of  opinion  than  any 
other  subject  in  the  internal  combustion  engine  field.  Although 
no  distinct  line  is  drawn,  a  motor  that  has  a  stroke  exceeding  lJ/£ 
times  the  bore  is  generally  spoken  of  as  a  "  long  stroke  "  motor, 
and  any  having  a  smaller  ratio,  as  a  "  short  stroke  "  motor.  As 
the  advocates  of  both  types  lay  claim  to  every  conceivable  advan- 
tage, the  subject  will  not  be  discussed  here  other  than  to  say  that 
increasing  the  stroke  increases  the  expansion  and  also  the  loss  by 
radiation  due  to  the  longer  contact  of  the  gases  each  stroke  with 
the  cylinder  walls.  It  increases  the  piston  speed ;  and  reducing 
the  bore  to  maintain  the  same  power,  it  increases  the  ratio  of 


OPERATION,    TROUBLES,    AND    REMEDIES.  99 

cylinder  wall  to  cylinder  contents,  hence  increases  loss  by  radia- 
tion. 

The  duty  for  which  the  motor  is  designed,  the  necessary  piston 
speed,  power  required,  weight  allowed  and  initial  compression, 
must  regulate  the  bore  and  stroke  to  a  large  extent. 


360'          /BO*  360  /80°          360'  /So' 


/Cyc/e.  2  Sfratres.  /Cyc/e      2  Strokes. 


0'  I6O°        J60*         /Go'          360'         /8O'         3€0"         SGO°         360* 

Cyc/e     -^  Cy///?c/er. 


O'  /Go'  360'          /eo'  360°          /Go'  360"          /8o"  36O" 

FIG.  62.— Pressure  Diagrams,  Showing  the  Effect  of  Multiplying 
Cylinders. 

Clearance. — The  clearance  volume  is  the  space  enclosed  by 
the  piston  head,  cylinder  walls  and  valve  recesses,  when  the  piston 
is  at  the  beginning  of  its  stroke.  The  proportion  of  the  clearance 
volume  to  the  piston  displacement  is  much  higher  than  in  the 
steam  engine,  because  all  the  medium  is  present  in  the  cylinder  at 
the  beginning  of  the  stroke  instead  of  being  admitted  during  a 
fraction  of  the  stroke  as  in  the  steam  engine.  This  statement 
does  not  apply  to  the  Diesel  and  similar  oil  engines.  Its  value 
depends  upon  the  kind  of  fuel  used,  sometimes  exceeding  35  per 
cent.  Obviously  the  higher  that  the  fuel  can  be  compressed,  the 
less  clearance  that  will  be  necessary. 


100  INTERNAL    COMBUSTION    ENGINE)    MANUAL. 

Scavenging. — Scavenging  a  cylinder  consists  of  driving  out 
the  burned  gases  before,  or  simultaneously  with,  the  entrance  of 
a  new  charge.  This  is  very  imperfect  with  an  ordinary  four  cycle 
motor,  for,  at  the  instant  of  admission,  all  the  clearance  volume 
is  full  of  the  burned  gas.  Those  engines  which  receive  the  air 
and  fuel  separately  can  be  scavenged  thoroughly  by  admitting  the 
air  while  the  exhaust  port  is  still  open  and  driving  out  the  exhaust 
gases  by  this  air  before  the  fuel  valve  opens.  Two  cycle  engines 
require  thorough  scavenging.  A  study  of  the  cycle  shows  that 
upon  this  depends  the  volume  of  fresh  mixture  that  can  be  taken 
into  the  cylinder,  and  as  the  two  cycle  exhausts  just  past  the 
center  of  the  expansion  stroke,  instead  of  at  the  end  as  in  the 
four  cycle,  scavenging  is  of  more  importance  in  the  former  case. 
This  is  generally  accomplished  by  allowing  some  of  the  fresh 
charge  to  enter  while  the  exhaust  port  is  still  open.  A  proper 
design  of  exhaust  will  aid  scavenging  by  giving  the  exhaust  gases 
a  high  speed,  causing  a  tendency  toward  a  partial  vacuum  in  the 
exhaust  line. 


CHAPTER  X. 

GASOLINE,   KEROSENE,  AND   ALCOHOL   ENGINES. 
Navy    Type    Engine. 

This  two-cycle,  three  port,  gasoline  engine,  the  action  of  which 
is  described  and  illustrated  on  pages  38  and  39,  was  developed 
by  the  Norfolk  Navy  Yard  to  meet  exacting  service  in  Naval 
launches  after  it  was  demonstrated  by  years  of  trial  and  test  that 
no  commercial  engine  then  on  the  market  quite  answered  Service 
requirements.  All  parts  are  made  from  standard  metal  patterns, 
insuring  interchangeability. 


FIG.  63. — Cylinder  and  Cover,  Navy  Type  Motor. 

Four  models  are  built,  viz :  EE,  one  cylinder ;  GG,  two  cylin- 
der; HH,  three  cylinder;  and  KK,  four  cylinder.  They  are 
rated  at  five  brake  horse-power  per  cylinder  at  500  revolutions 
per  minute,  bore  4^  inches,  and  stroke  5  inches. 

Cylinders  are  of  special,  hard,  close  grained  iron,  provided 
with  removable  heads,  which,  together  with  the  cylinders,  are 
amply  water  jacketed.  Cylinder  jackets  are  provided  with  large 
access  plates  (Fig.  63). 

Pistons  are. cast  of  the  same  material  as  the  cylinders,  care- 
fully turned  and  taper  ground,  and  are  fitted  with  four  eccentric 


102 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


rings,  three  at  the  top  and  one  at  the  bottom.     Below  the  latter 
are  two  oil  grooves  (see  Fig,  10). 

Connecting  Rods  are  drop-forged  steel  of  I-beam  section,  the 
•crank  pin  end  being  fitted  with  babbit  lined,  removable  brasses, 
made  in  halves.  The  upper  end  is  rigidly  secured  to  the  wrist 
pin,  which  is  of  hollow  hardened  steel  (Fig.  10). 


FIG.  64.— Crank  Shaft,  Pistons,  Flywheel. 

Crank  Shafts  are  special  carbon  steel  drop-forgings,  machined 
and  ground  to  .001  inch  and  are  carefully  balanced  (Fig.  64). 

Crank  Cases  are  designed  to  give  the  correct  crank  case  com- 
pression. They  are  made  in  two  halves,  dividing  on  the  shaft 
center  line.  Crank  shaft  bearings  are  fitted  with  removable, 
babbit-lined  brasses,  made  in  halves. 


FIG.  65. — Plunger  Type  Circulating  Pump. 

Pumps. — A  plunger  circulating  pump  is  driven  from  the  crank 
shaft.  A  bilge  pump  of  the  same  construction  is  supplied  with 
all  but  the  one  cylinder  engine  (Fig.  65). 

Lubrication  is  by  crank  case  splash  system  and  by  Detroit 
forced  feed  mechanical  lubricator,  as  described  on  page  75. 
Grease  cups  are  located  at  necessary  external  bearings. 


GASOLINE,    KEROSENE,    AND    ALCOHOL  ENGINES.  103 

Ignition  is  of  the  high  tension,  jump  spark  type,  using  Bosch 
high  tension  magneto.  The  two  larger  engines  use  a  Dual  or 
Duplex  system  with  battery. 

Carburetion. — The  carburetor  is  a  Model  D,  Schebler,  de- 
scribed on  page  46.  The  inlet  manifolds  are  of  copper.  The  ex- 
haust manifolds  are  water  jacketed.  An  ejector  type  muffler  is 
used,  circulating  water  being  discharged  through  it. 

The  Standard  Submarine  Chaser  Engine. 

The  Standard  Engine  for  110-foot  submarine  chasers,  Fig.  66, 
built  by  the  Standard  Motor  Construction  Company,  is  a  six 
cylinder,  single  acting,  four  cycle,  gasoline  engine  of  220  brake 
horse-power  at  460  revolutions  per  minute;  bore  10  inches,  and 
stroke  11  inches.  It  weighs  about  30  pounds  per  horse-power 
and  has  a  guaranteed  fuel  consumption  of  not  more  than  one 
pint  per  horse-power  hour  at  full  power. 

The  Engine  Frame  is  built  of  turned  steel  stanchions,  cross 
braced,  and  the  bed  plate  is  of  cast  iron.  It  has  planed  web  sup- 
ports for  the  main  bearings. 

Main  Bearings  are  split  and  set  in  the  bed  plates.  They  are 
of  phosphor  bronze  and  provided  with  oil  grooves.  The  upper 
caps  are  recessed  in  the  bed  plate. 

Cylinders  are  cast  separately  of  hard  close  grained  iron,  with 
removable  heads.  Cylinders  and  heads  have  large  water  jackets, 
the  heads  receiving  circulating  water  externally,  independently  of 
the  cylinders.  Substantial  lugs  are  cast  on  the  cylinders  for 
bolting  to  the  steel  stanchions. 

Pistons  are  of  hard  close  grained  cast  iron.  The  wrist  pin  is 
secured  to  the  piston ;  the  connecting  rod  works  on  the  pin. 

Connecting  Rods  are  of  nickel  steel.  The  upper  ends  are  fitted 
with  phosphor  bronze  bushings,  and  the  lower  ends  are  fitted  with 
split  phosphor  bronze  bearings.  Both  ends  are  provided  with  oil 
grooves. 

The  Crank  Shaft  has  seven  point  suspension,  and  has  six 
throws  arranged  at  120°  interval.  It  is  a  one-piece  nickel  steel 
forging,  carefully  machined  all  over. 

Valves  and  Valve  Gear. — The  inlet  valves  are  automatic,  spring 
loaded,  steel  mushroom  valves,  with  long  hollow  stems  that  slide 
in  phosphor  bronze  bushings  in  the  valve  stem  guides.  They  are 


104  INTERNAL,    COMBUSTION    ENGINE)    MANUAL. 

provided  with  dash  pots  and  spiral  springs  to  absorb  the  shock  of 
quick  opening.  The  exhaust  valves  are  of  cast  iron,  hollow,  bal- 
anced, and  water  cooled.  They  are  operated  by  nickel  steel 
rocker  arms  with  pull  rods  under  tension,  the  pull  rods  being 
actuated  by  the  cam  shaft. 

The  Cam  Shaft  is  of  steel  supported  in  split  bronze  bearings 
bolted  on  the  stanchions.  There  are  three  sets  of  nickel  steel 
cams  on  the  shaft,  one  for  the  exhaust  valves,  one  for  the  igniter 
rods,  and  one  for  the  air  starting  valves.  The  cams  are  ground, 
finished,  hardened  and  keyed  on  the  shaft.  The  cam  shaft  is 
operated  from  the  main  shaft  through  a  vertical  shaft.  The 
driving  gear  on  the  cam  shaft  has  a  sliding  key-way  which  allows 
the  cam  shaft  to  shift  in  a  fore  and  aft  direction  while  the  gears 
are  always  in  mesh.  This  permits  the  air  starting  valves  being 
thrown  into  action  for  starting.  The  fuel  pump  and  magneto  are 
driven  off  the  vertical  shaft. 

An  operating  lever  at  the  after  end  of  the  engine  slides  the 
cam  shaft  in  a  fore  and  aft  direction  for  starting.  At  the  opposite 
end  of  the  engine  is  a  small  single  stage  air  compressor  cylinder 
for  supplying  air  at  250  pounds  pressure  to  the  compressed  air 
tank.  This  is  used  for  starting  and  for  the  whistle. 

The  Circulating  Pump,  of  ample  size,  of  the  double  action 
type,  is  operated  from  the  crank  shaft  by  gearing.  Water  from 
the  pump  is  delivered  to  the  cylinders  and  heads  and  to  the  ex- 
haust valves.  The  inlet  gasoline  manifold  is  jacketed  by  the  hot 
circulating  water. 

Fuel  System. — Gasoline  flows  by  gravity  from  the  fuel  tank 
through  a  strainer  to  a  float  box,  which  is  a  small  cast  iron  box 
containing  a  float  which  maintains  a  constant  level  in  the  box. 
The  fuel  pump  has  a  suction  connection  to  this  box  and  dis- 
charges to  the  vaporizer.  The  vaporizer  is  of  the  multiple  jet 
type,  receiving  its  fuel  from  the  fuel  pump,  and,  being  under  a 
vacuum  from  the  engine  suction,  discharges  its  vapor  to  the  in- 
take manifold.  The  air  and  gasoline  are  both  regulated  for  the 
engine  speed. 

Ignition  is  by  the  make  and  break  system,  current  being  sup- 
plied by  a  simple  low  tension  magneto.  A  battery  is  used  for 
starting  and  for  running  astern. 

Lubrication  is  principally  by   forced  feed  through  individual 


GASOLINE,    KEROSENE,    AND    ALCOHOL  ENGINES.  105 


FIG.  66. — Standard  Submarine  Chaser  Engine. 


io6 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


GASOLINE:,  KEROSENE,  AND  ALCOHOL  ENGINES. 


107 


feed  pipes  to  the  different  running  parts.  There  is  no  enclosed 
crank  case.  The  forced  feed,  lubricator  is  attached  to  the  side  of 
the  forward  cylinder.  Seventeen  pumping  units  in  this  supply 
oil  to  seventeen  feed  pipes  that  run  to  all  the  parts  to  be  lubri- 
cated. Each  pumping  unit  is  a  double-plunger  valveless  pump. 
One  plunger  pumps  the  oil  from  the  reservoir  through  the  sight 
feed  nozzle  to  the  feed  chamber,  the  other  takes  it  from  this 
chamber  and  forces  it  to  the  engine  parts. 

All  pumping  units  are  actuated  by  a  drive  shaft  which  in  turn 
is  driven  off  the  cam  shaft.  One  end  of  the  drive  shaft  is  fitted 
with  a  handle  for  working  the  pumps  before  starting  the  engine. 


^ 
FIG.  68 — Vaporizer,  Submarine  Chaser  Engine. 

By  an  adjustable  ratchet  arm  in  the  driving  mechanism  the  pump 
stroke  can  be  regulated  to  the  amount  of  oil  required.  For 
smaller  adjustments  of  oil  feed  there  is  one  adjusting  button  on 
the  oiler  cover  in  front  of  each  sight  feed  nozzle.  The  pipes 
from  the  lubricator  supply  oil  to  the  following  points :  Each 
main  bearing,  each  crank  pin  oil  ring,  each  cylinder  and  wrist 
pin,  circulating  pump  main  bearing,  vertical  cam  shaft  bearing, 
spiral  gear  of  vertical  cam  shaft,  eccentric  driving  air  compres- 
sor, air  cylinder  and  wrist  pin,  thrust  yoke,  each  exhaust  valve. 
Such  few  other  parts  as  require  lubrication  are  oiled  by  hand 
hourly. 


108  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

The  Standard  Double  Acting   Engine. 

This  gasoline  engine  designed  for  marine  use  is  made  in  units 
of  three  cylinders,  and  generally  installed  as  a  two  unit  plant  or 
six  cylinder  engine.  It  is  four  cycle,  double  acting,  having  an  ad- 
mission and  exhaust  valve  for  both  top  and  bottom  of  each 
cylinder.  This  gives  the  engine  the  equivalent  of  twelve  working 
cylinders.  The  engine  is  water  cooled,  as  are  all  the  pistons, 
connecting  rods,  valves,  and  the  exhaust  manifold. 

The  admission  valves  are  all  on  the  front  of  the  engine,  and 
are  mechanically  operated  from  the  same  cam  shaft.  The  ex- 
haust valves  on  the  back  of  the  engine  are  similarly  operated  by 
another  cam  shaft.  All  valves  are  mushroom  shaped  of  the  bal- 
anced type. 

To  reduce  the  power  to  one-half  all  the  bottom  admission 
valves  can  be  locked  closed  and  the  exhaust  valves  open,  making 
the  engine  six  cylinder  single  acting.  To  reduce  to  one- fourth 
power  the  two  units  can  be  disconnected  and  one  unit  run  as  a 
three  cylinder  single. acting  engine.  The  engines  are  built  to  250 
horse-power  per  three  cylinder  unit.  A  twin  screw  marine  plant 
of  1,000  horse-power  can  be  furnished  by  the  manufacturers. 

The  piston  is  short,  being  somewhat  similar  .to  a  steam  engine 
piston,  and  consequently  a  cross  head  and  guide  are  necessary. 
The  piston  rod  works  through  a  metallic  packed  stuffing  box  to 
make  the  bottom  end  of  the  cylinder  gas  tight.  Forced  feed 
lubrication  is  employed.  Ignition  is  by  the  make  and  break 
system. 

In  Fig.  69,  A  is  the  gas  inlet,  B  the  top  admission,  C  the  top 
exhaust,  and  D  the  exhaust  outlet.  It  is  apparent  that  this  will 
operate  as  a  four  cycle  engine.  On  the  bottom  end,  B^  is  the  bot- 
tom admission,  and  C^  the  bottom  exha*ust.  This  end  also  acts  as 
an  independent  four  cycle  engine.  E  and  F  are  the  cam  shafts 
that  operate  the  admission  and  exhaust  valves,  respectively. 

The  engine  is  operated  by  the  two  levers,  G  and  H,  shown  on  the 
front  of  the  engine.  G  is  the  spark  lever.  The  lever  H  operates 
a  compressed  air  valve  which,  in  turn,  can  shift  the  admission 
valve  cam  shaft  in  the  direction  of  its  length.  This  shaft  carries 
three  sets  of  cams.  One  operates  the  admission  valves  for  ahead 
direction,  one  for  reverse  direction,  and  one  set  operates  air 
valves  in  the  bottom  of  the  three  after  cylinders  for  starting  and 
reversing. 


GASOLINE,    KEROSENE,    AND    ALCOHOL  ENGINES. 


FIG.  69.— Standard  Engine. 


I  IO 


INTERNAL    COMBUSTION    ENGINE;    MANUAL- 


FIG.  70.—  Mietz  and  Weiss  Oil  Engine. 


GASOLINE,    KEROSENE,    AND    ALCOHOL  ENGINES.  I  I  I 

The  Mietz  and  Weiss  Marine  Oil  Engine. 

The  Mietz  and  Weiss  is  a  two-cycle  marine  oil  engine  that 
operates  on  the  Semi-Diesel  principle,  using  kerosene,  fuel  or 
crude  oil.  Its  fuel  consumption  is  about  one  pint  of  oil  per 
horse-power  hour  at  all  loads. 

Fig.  70  shows  a  cross  section  of  the  engine.  The  piston  is  of 
the  trunk  pattern  fitted  with  cast  iron  packing  rings.  The  cylin- 
ders are  amply  water- jacketed;  circulation  is  by  a  rotary  pump 
driven  by  gear  from  the  main  shaft.  Circulating  water  enters  the 
base  of  the  jacket,  is  forced  up  to  the  top  and  is  led  into  the 
exhaust  pipe  to  prevent  overheating  of  the  latter.  This  is  a  com- 
mon marine  practice. 

Fuel  is  supplied  by  a  pump  which  is  governor  regulated  so  that 
the  amount  of  fuel  supplied  is  a  function  of  the  speed  and  load. 
The  fuel  enters  the  cylinder  by  the  pipe  57  and  encounters  the  hot 
bulb  64,  which  vaporizes  and  ignites  it.  Waste  gases  pass  out  at 
the  exhaust  .139.  When  the  engine  is  to  be  started  cold  the 
bulb  must  be  heated  to  dull  red  heat  by  an  external  burner  176. 
After  the  first  explosion  the  bulb  will  retain  its  heat  and  the 
ignition  is  by  a  combination  of  compression  and  hot  bulb. 

Lubrication  is  by  forced  feed,  the  oil  pump  consisting  of  a 
plunger  worked  by  a  ratchet,  the  lubrication  of  the  cylinder, 
piston,  crank  pins,  shaft  bearings  and  connecting  rods  being  abso- 
lutely automatic.  An  engine  of  this  type  is  installed  in  the  lab- 
oratory. 


112  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

Knight  Slide  Valve  Motor. 

The  impact  of  poppet  valves  on  their  seats,  and  the  cams, 
springs,  etc.,  which  operate  them,  are  a  source  of  noise  in  an  en- 
gine. This  noise  is  eliminated  in  the  Knight  motor.  The  princi- 
pal advantage  claimed  for  this  valve  mechanism  is  that  the  inlet 
and  exhaust  passages  are  fully  twice  the  size  of  the  gas  passage 
obtainable  in  a  liberal  design  of  the  tee-head  poppet  valve  motor, 


FIG.  71. — Columbia  Knight  Motor,  Showing  Sleeve-Valve  Arrangement. 

and  nearly  three  times  the  size  of  the  gas  passages  in  the  ell-head 
or  valve-in-head  motor. 

Figs.  71,  72  and  73  show  the  general  features  of  design  as 
adopted  by  the  United  Motor  Company  in  the  Columbia.  The 
cylinder  heads  are  removable.  They  are  depressed,  water-cooled 
and  contain  two  spark  plugs  for  Bosch  or  other  double  ignition. 


GASOLINE,    KEROSENE,    AND    ALCOHOL  ENGINES.  113 

The  valves  for  each  cylinder  consist  of  two  sleeves  made  of  very 
hard  Swedish  grey  iron.  Both  inner  and  outer  sleeves  are  open 
at  both  ends  and  each  sleeve  has  openings  on  two  sides.  These 
sleeves  are  reciprocated  to  perform  the  valve  function  by  short 
connecting  rods  actuated  by  a  lay  crankshaft  at  half  speed  by 
"  Coventry  "  silent  chain. 


FIG.  72. — Columbia  Knight  Motor,  Cross-Section  View. 

As  seen  from  the  cuts  the  outer  sleeve,  driven  by  a  connecting 
rod  from  a  countershaft  on  the  right,  Fig.  72,  moves  up  and  down 
between  the  cylinder  wall  and  the  inner  sleeve.  The  inner  sleeve, 
driven  by  its  connecting  rod  from  the  same  countershaft,  Fig. 
71,  moves  up  and  down  between  the  outer  sleeve  and  the  piston. 
The  inner  wall  of  this  inner  sleeve  forms  the  combustion  chamber 
wall. 

8 


114  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

The  travel  of  the  sleeves  is  only  about  one  inch  and  the  power 
required  to  overcome  their  friction  and  drive  them  is  no  greater 
than  that  necessary  to  actuate  poppet  valves  for  an  engine  of  the 
same  size.  The  eccentric  driving  the  inner  sleeve  is  given  a  cer- 
tain advance  or  "  lead  "  over  that  driving  the  outer  one. 

Operation. — During  the  suction  stroke  the  right-hand  slots  of 
the  inner  and  outer  sleeves  register,  forming  a  large  opening  for 
the  charge  to  enter.  At  the  end  of  the  suction  stroke  one  sleeve 


,  Inlet  opens.      2,  Inlet  open.  3.  Inlet  closes.        4.  Top  of         5.  Exhaust  opens.       6.  Exhaust  open.    7.  Exhaust  closes. 

compression  stroke. 


FIG.  73. — Relative  Positions  of  Sleeves  and  Piston  in  the  Operation 
of  the  Knight  Engine. 


moves  up  and  the  other  down,  closing  the  opening,  and  the  com- 
pression stroke  takes  place.  Compression  being  accomplished,  the 
charge  is  fired  in  the  usual  way  and  the  combustion  or  power 
stroke  takes  place,  all  slots  still  being  out  of  register.  At  the 
end  of  the  power  stroke,  movement  of  the  sleeves  brings  the 
left-hand  slots  into  register,  and  the  opening  thus  formed  is  a 
large  exhaust  for  the  gases.  This  is  best  illustrated  by  Fig.  73, 
which  shows  seven  points  in  one  complete  cycle. 


GASOLINE,    KEROSENE,    AND    ALCOHOL    ENGINES.  115 

The  timing  shown  is  not  different  from  that  ordinarily  used  in 
poppet  valve  engines.  Timing  of  the  valves  is  secured  by  varying 
the  lead  between  the  eccentrics  that  operate  the  two  sleeves  and 
by  properly  locating  the  slots  in  the  sleeves.  The  amount  of  valve 
opening  is  practically  unlimited  and  is  governed  by  the  width  of 
the  slot  in  the  sleeves  and  the  throw  of  the  eccentrics  that  drive 
and  determine  the  travel  of  the  sleeves. 

The  Alcohol  Engine. 

The  problem  of  alcohol  vaporization  was  discussed  under  the 
chapter  on  carburetion.  In  appearance  the  engine  is  like  an 
ordinary  four  cycle  gasoline  engine,  but  in  design,  since  the 
useful  effect  of  a  given  weight  of  denaturized  alcohol  is  0.7  that 
of  an  equal  weight  of  gasoline,  the  cylinder  dimensions,  inlet  and 
exhaust  passages,  are  increased  in  the  ratio  of  1.4  to  1  to  get 
equal  power.  This  increase  and  the  modified  carburetor  are  the 
only  points  wherein  the  alcohol  engine  differs  from  the  gasoline 
engine.  The  compression  is  carried  higher  than  in  other  liquid 
fuel  engines.  Recent  experiments  show  that  the  alcohol  engine 
can  be  started  cold.  The  Deutz  Company  spray  the  alcohol  into 
the  admission  line  near  the  inlet  valve.  A  mixture  of  equal 
weights  of  gasoline  and  alcohol  gives  a  very  efficient  performance 
in  the  gasoline  engine  without  necessitating  change  of  cylinder 
design. 


CHAPTER  XL 

AERIAL    MOTORS. 

The  vast  strides  in  aeronautical  development  due  to  demands 
of  the  present  war,  culminating  in  the  enormous  900  H.P.  Caproni 
triplane  of  Italy,  capable  of  carrying  three  tons,  and  the  attendant 
talk  of  the  United  States  winning  the  war  with  a  vast  fleet  of  aero- 
planes, makes  this  type  of  engine  of  particular  interest  at  the  time 
of  writing.  It  is  regretted  that  the  scope  of  this  book  precludes 
a  more  comprehensive  presentation  of  the  subject.  Aeroplane 
development  is  limited  only  by  the  degree  of  development  of  the 
gasoline  engine. 

The  Essential  Features  for  a  successful  aerial  motor,  in  the 
order  of  their  military  importance,  are  (1)  fuel  and  oil -economy, 
(2)  lightness,  (3)  reliability,  (4)  durability,  (5)  efficiency  under 
varying  operating  conditions,  (6)  accessibility,  .and  (7)  sim- 
plicity. 

(1)  Economy,  fuel  aftd  oil,  is  essential  because  the  radius  of 
flight  is  limited  by  the  amount  of  fuel  and  lubricant  the  machine 
can  carry.    This  is  closely  related  to 

(2)  Weight  of  Power  Plant. — A  true  comparison   of   aero- 
plane motors  can  be -made  only  by  considering  the  gross  weight 
of  the  complete  power  plant,  with  fuel  and  oil,  for  the  duration 
of  a  flight.     In  such  a  comparison  the  great  advantage  of  fuel 
economy  is  evident;  in  a  light  but  uneconomical  motor  it  may 
even  outweigh  the  advantage  of  light  weight  of  motor.     For 
example,  the  fuel  and  oil  consumption  of  a  well  designed  four- 
cycle motor  is  about  .53  pound  per  H.P.  hour,  while  the  gross 
weight  for  a  ten  hour  flight  is  about  11^2    pounds  per  H.P., 
whereas,  the  corresponding  fuel  and  oil  consumption  and  weight 
per  horse-power  of  a  light  rotary  motor  are  about  .9  pound  and 
14  pounds.     Obviously  if  the  requirements  are  a  ten  hour  flight, 


AERIAL    MOTORS.  1 17 

the  former  engine  is  preferable.  Light  motor  weight  is  a  matter 
of  design,  materials  and  workmanship.  Recently  aluminum 
alloys  of  copper,  zinc,  tin,  magnesium,  nickel,  tungsten,  chromium 
and  antimony  have  played  a  most  important  part  in  weight  re- 
duction. They  are  used  successfully  for  crank  cases,  cylinders, 
pistons  and  for  many  minor  castings. 

(3)  Reliability  is  more  essential  in  the  aerial  motor  than  in 
any  other  type.    The  nature  of  the  medium  in  which  the  machine 
operates  and  the  fact  that  sustained  flight  is  only  possible  when 
the  motor  is  functioning  properly  makes  this  imperative. 

(4)  Durability. — Aerial  motors  have  a  shorter  life  than  any 
other  type  gasoline  engine  because  they  are  designed  lighter  per 
horse-power  (about  1/3  the  weight  of  the  automobile  engine), 
and,  in  service,  their  normal  operation  is  at  full  power  for  long 
periods. 

(5)  Efficiency  under  varying  load  conditions  is  essential.    Very 
little  flying  is  done  at  ordinary  levels,  the  very  nature  of  the 
service    required    from    a   military    machine    involves    sustained 
flights  at  high  levels.     As  a  machine  ascends  the  air  becomes 
rarified,  the  atmospheric  pressure  decreasing  3%  to  4%  per  1,000 
feet  above  sea  level.     As  a  result  the  power  developed  by  the 
engine  decreases  as  the  machine  ascends. x  The  reason  for  this  is 
that,  as  the  air  pressure  is  reduced,  the  pressure  at  the  end  of  the 
suction  stroke  is  decreased,  and,  as  a  result,  the  pressure  at  the 
end  of  the  compression  stroke  is  less.    Reducing  the  compression 
decreases  the  power. 

(6)  Accessibility  of  parts  to  facilitate  adjustments  and  repairs 
is»very  desirable. 

(7)  Simplicity  is  essential  because  only  by  constant  inspection 
and  overhaul  can  successful  operation  be  insured. 

Characteristics. — All  successful  aeroplane  motors  are  single 
acting,  use  gasoline  for  fuel,  and  nearly  all  are  four-cycle.  Both 
water  and  air  cooled  motors  are  in  use,  rotary  motors  being  air 
cooled  as  a  rule.  Radiators  are  similar  to  but  lighter  than  those 
used  in  automobiles,  and  are  specially  designed  to  reduce  head 
resistance.  Engines  for  aerial  work  must  be  carefully  balanced 


Il8  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

to  eliminate  vibration.  Small  motors  are  started  by  hand  from 
the  operator's  seat,  but  motors  of  150  H.P.  and  over  are  gen- 
erally fitted  with  an  air  actuated  self-starter. 

Types. — Aeroplane  motors  may  be  classed  as  follows  :  (1)  Ver- 
tical, (2)  Diagonal  or  "V"  type,  (3)  Horizontal  opposed,  (4) 
Radial,  and  (5)  Rotary. 

1.  Vertical  Aeroplane  Engines. 

The  vertical  type  of  aeroplane  engine  is  a  development  from 
the  automobile  engine.  It  is  distinguished  by  its  light  weight,  per- 
fect balance,  and  other  features  of  design  adapted  to  its  particular 
field.  Thus,  when  the  machine  is  upside  down,  there  must  be  no 
danger  of  fire  and  the  carburetor  must  function  perfectly.  Prac- 
tically all  vertical  engines  have  two  spark  plugs  per  cylinder  (two 
point  ignition). 

Hall-Scott  Model  A-5  Motor,  Fig.  74.— This  is  a  vertical, 
water-cooled  six  cylinder,  four  cycle  engine  of  125  H.P.  at  1,300 
revolutions  per  minute,  with  a  4-inch  bore  and  5-inch  stroke.  It 
weighs  about  5  pounds  per  H.P. 

Cylinders  are  cast  separately  of  semi-steel  (a  special  mixture 
of  grey  and  Swedish  iron)  with  integral  cylinder  heads,  great 
care  being  exercised  in  casting  and  machining  these  to  have  the 
bore  and  walls  concentric  with  each  other.  Small  ribs  are  cast 
between  the  outer  and  inner  walls  to  assist  cooling  and  to  transfer 
stresses  direct  from  the  explosion  to  holding-down  bolts  that  run 
from  the  main  bearing  caps  to  the  cylinder  tops.  Ample  water 
jackets  are  provided  around  the  head  and  valves,  there  being  two 
inches  of  water  space  above  the  latter. 

,  The  cylinder  is  annealed,  rough  machined,  then  the  inner  cylin- 
der wall  and  valve  seats  are  hardened  and  ground  to  mirror 
finish  to  add  to  the  durability  of  the  cylinder  and  to  diminish 
friction.  The  cylinder  sides  are  machined  so  that  when  assembled 
on  the  crank  case  the  cylinders  form  a  solid  block. 

Pistons  are  cast  from  the  same  semi-steel  mixture  as  the  cylin- 
ders ;  they  are  extremely  light,  and  are  provided  with  six  deep 
ribs  under  the  arch  head.  Pistons  are  first  annealed,  machined 


AERIAI,    MOTORS. 


close  to  size,  and  then  hardened  and  ground  to  a  mirror  finish. 
The  piston  pin  bosses  are  located  very  low  so  that  the  heat  from 
the  piston  head  is  kept  as  far  from  the  upper  end  of  the  connect- 
ing rod  as  possible.  There  are  three  54 -inch  piston  rings. 

Connecting  Rods  are  of  the   I-beam  type,  milled   from  solid 
chrome  nickel  forgings,  and  are  well  balanced.    The  piston  end  is 


FIG.  74.— Hall-Scott,  Model  A-5,  Aeroplane  Motor. 


120  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

fitted  with  a  gunmetal  bushing.  The  crank  pin  end  carries  two 
bronze  serrated  shells,  which  are  tinned  and  babbitted  hot  and 
broached  to  harden  the  babbitt. 

The  Crank  Shaft  is  of  the  seven  bearing  type,  being  cut 
from  a  billet  of  chrome  nickel  steel  of  275,000  pounds  tensile 
strength.  The  bearing  surfaces  are  extremely  large,  this  being  ac- 
complished without  undue  length  of  motor  by  offsetting  the  webs 
of  the  shaft,  a  novel  feature.  This  offset  acts  as  an  oil  scooper 
for  oiling  the  connecting  rods.  Two  thrust  bearings  are  installed 
on  the  propeller  end  of  the  shaft,  one  for  pull  and  one  for  push. 
Timing  gear  and  starting  ratchets  are  bolted  to  a  flange  turned 
integral  with  the  shaft. 

The  Cam  Shaft  is  a  one  piece,  low  carbon  chrome  nickel  steel 
forging,  cams,  air  pump  eccentrics,  and  gear  flange  being  integral. 
It  is  enclosed  in  an  aluminum  housing  bolted  directly  on  top  of 
all  six  cylinders,  being  driven  by  a  vertical  shaft  in  connection 
with  bevel  gears.  This  shaft,  in  conjunction  with  rocker  arms, 
rollers  and  other  working  parts,  are  oiled  by  forcing  the  oil  into 
the  end  of  the  shaft,  using  same  as  a  distributor,  allowing  the 
surplus  supply  to  flow  back  into  the  crank  case  through  the  hollow 
vertical  tube.  This  supply  oils  the  magneto  and  pump  gears. 

Valves. — Extremely  large  tungsten  valves,  one-half  the  cylinder 
diameter,  are  seated  in  the  cylinder  head  and  are  operated  by  the 
overhead  one-piece  cam  shaft  in  connection  with  short  chrome 
nickel  rocker  arms.  These  arms  have  hardened  tool  steel  rollers 
on  the  cam  end,  with  hardened  tool  steel  adjusting  screws  oppo- 
site. This  construction  allows  accurate  valve  timing  at  all  speeds 
with  least  possible  weight. 

Large  diameter  oil  tempered  springs  held  in  tool  steel  cups 
locked  with  a  key  are  provided.  The  ports  are  very  large  and 
short,  being  designed  to  allow  the  gases  to  enter  and  exhaust 
with  the  least  possible  resistance. 

Gears. — All  gears,  with  the  exception  of  the  two  bronze  oil 
pump  gears,  are  of  chrome  nickel  steel  and  where  possible  are 
bolted  to  flanges  or  made  integral  with  the  shaft,  and  are  enclosed 
to  run  in  oil. 


AERIAL    MOTORS.  121 

Crank  Case  and  Oil  Sump  are  cast  of  aluminum  alloy,  hand 
scraped  and  sand  blasted  inside  and  out.  The  lower  oil  case  can 
be  removed  without  breaking  any  connections,  giving  access  to 
the  connecting  rods  and  other  working  parts.  The  lower  case 
holds  eight  gallons  of  oil. 

Carburetion. — A  double  Zenith  carburetor,  having  one  float 
chamber,  is  provided.  Automatic  valves  and  springs  are  absent, 
making  the  adjustment  simple  and  efficient.  This  carburetor  is 
not  affected  by  altitude.  It  is  bolted  directly  to  the  engine  base 
from  which  it  receives  its  warm  air.  This  also  tends  to  keep  the 
crank  case  cool.  A  Hall-Scott  device,  covered  by  U.  S.  patent, 
circulates  the  oil  from  the  crank  case  around  the  carburetor  mani- 
fold, thus  assisting  carburetion  as  well  as  reducing  crank  case 
temperature. 

Ignition. — Two  six  cylinder  Bosch  magnetos  furnish  current, 
there  being  a  set  of  spark  plugs  for  each  magneto.  Both  magneto 
interrupters  are  connected  to  a  rock  shaft  integral  with  the 
motor,  making  outside  connections  unnecessary. 

It  is  worthy  of  note  that  with  this  independent  double-magneto 
system  one  complete  magneto  can  become  indisposed  and  still 
the  motor  will  run  and  continue  to  give  more  than  three-quarter 
power. 

Lubrication  is  by  the  high  pressure  system,  oil  being  forced  to 
the  under  side  of  the  main  bearings  at  a  pressure  of  five  to  thirty 
pounds.  This  system  is  not  affected  by  the  extreme  angles  ob- 
tained in  flying.  A  large  geared  pump  runs  submerged  in  the 
lowest  point  of  the  oil  sump,  thus  doing  away  with  troublesome 
stuffing  boxes  and  check  valves. 

Oil  is  first  drawn  from  the  strainer  in  the  oil  sump  to  the  long 
jacket  around  the  intake  manifold,  then  it  is  forced  to  the  main 
distributor  pipe  in  the  crank  case  which  leads  to  all  main  bearings. 
A  by-pass  located  at  one  end  of  the  distributor  pipe  regulates  the 
oil  pressure,  the  surplus  oil  being  returned  to  the  case. 

Independent  of  this  system,  a  small  six-plunger  pump  feeds  oil 
to  each  individual  cylinder.  The  stroke  of  the  plungers  can  be 
separately  adjusted  to  regulate  this  supply.  A  strainer  and  a 


122 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


dirt,  water  and  sediment  trap  are  located  at  the  bottom  and  center 
of  the  oil  sump.  This  can  be  removed  without  disturbing  the  oil 
pump  or  any  oil  pipes.  A  small  oil  pressure  gage  on  the  instru- 
ment board  registers  the  oil  pressure. 


FIG.  75. — Cross  Section  of  V-Type  Motor. 

Cooling  System. — Cooling  this  motor  is  accomplished  by  oil  as 
well  as  by  water,  by  circulating  the  lubricating  oil  around  a  long 
intake  jacket.  The  carburetion  of  gasoline  cools  this  oil  and  the 
crank  case  heat  is  therefore  kept  at  a  minimum  regardless  of 
weather  conditions. 

The  water  is  circulated  by  a  large  centrifugal  pump,  that  pro- 
vides ample  circulation  at  all  speeds ;  water  enters  at  the  bottom 
of  the  water  jackets.  An  ingenious  internal  outlet  pipe  runs 
through  all  six  cylinders,  the  joints  being  made  with  packing  nuts. 


AERIAL    MOTORS.  123 

Slots  are  cut  in  this  pipe  in  each  water  jacket  so  that  the  circulat- 
ing water  is  drawn  directly  around  the  exhaust  valves.  This 
maintains  a  uniform  cylinder  temperature. 

A  Starting  Crank  is  mounted  in  a  compact  aluminum  housing 
securely  bolted  to  the  main  crank  case,  thus  forming  an  integral 
part  of  the  motor. 

2.  V  Type  Engines. 

It  is  obvious  that,  as  the  number  of  cylinders  of  a  vertical 
motor  is  increased,  the  crank  shaft  and  crank  case  become  very 
heavy  and  finally  the  number  of  cylinders  reach  a  limit;  modern 
designers  place  this  at  eight.  The  V  type  motor  is  designed  to  re- 
duce the  weight  for  a  given  number  of  cylinders  by  arranging 
them  at  an  angle  in  pairs,  the  case  and  shaft  being  common  to 
both  cylinders  of  a  pair. 

Thus  an  eight  cylinder  V  type  motor  has  its  cylinders  arranged 
in  two  sets  of  four  cylinders  each,  the  sets  being  opposite  one 
another  at  an  angle,  generally  90°,  the  connecting  rods  of  corre- 
sponding cylinders  of  the  two  sets  working  on  the  same  crank, 
Fig.  75.  An  eight  cylinder  motor  crank  shaft  has  four  cranks, 
each  crank  a  operating  two  connecting  rods,  b,  b.  The  cam  shaft 
c  is  driven  through  gearing  or  by  chain  drive  from  the  main  shaft 
a.  Each  cam  operates  two  push  rods,  d,  d. 

This  design  is  being  widely  adopted  both  here  and  abroad  for 
engines  of  eight  and  more  cylinders.  It  cannot  be  so  perfectly 
balanced  as  the  radial  or  rotary  engine,  but  to  offset  this  its  head 
resistance  is  less  than  either  of  those  types.  Nearly  all  V  type 
motors  are  water  cooled.  Eight  cylinder  motors  are  generally 
provided  with  two  magnetos,  one  for  each  bank  of  four  cylinders, 
and  twelve  cylinder  motors  generally  have  three,  one  for  each 
bank  of  four  cylinders. 

Sturtevant  Model  5  A  Motor,  Fig.  76. — This  is  a  V- 
type,  water  cooled,  eight  cylinder,  four  cycle  engine  of  140  H.P.  at 
2,000  revolutions  per  minute,  with  a  4-inch  bore  and  5-inch  stroke. 
It  weighs  4  pounds  per  H.P. 


124  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

Cylinders  are  cast  in  pairs  from  an  aluminum  alloy  with  a  steel 
liner.  A  molded  copper  asbestos  gasket  is  placed  between  the 
cylinder  and  head  insuring  a  tight  joint.  The  cylinder  heads  are 
cast  in  pairs  of  aluminum  alloy  with  ample  water  passages.  Each 
cylinder. is  held  to  the  base  by  six  long  bolts  which  also  pass 
through  the  heads. 

Pistons,  which  are  made  very  light  from  a  special  aluminum 
alloy  to  reduce  vibration  and  wear  of  bearings,  are  deeply  ribbed 
in  the  head  for  cooling  and  strength,  and  are  provided  with  two 
piston  rings.  The  wrist  pin  is  made  of  chrome  nickel  steel,  hollow 
bored  and  hardened ;  it  turns  in  both  piston  and  connecting  rod. 

Connecting  Rods  are  made  in  H-section  of  air  hardening 
chrome  nickel  steel,  having  a  tensile  strength  of  280,000  pounds 
per  square  inch.  The  crank  ends  are  lined  with  white  metal  and 
the  wrist  pin  ends  are  bushed  with  phosphor  bronze. 

Crank  Shaft. — This  is  machined  from  heat  treated  chrome 
nickel  steel.  It  is  2^4  inches  in  diameter  and  bored  hollow 
throughout  to  obtain  maximum  strength  with  minimum  weight. 
It  is  carried  in  three  large,  bronze  backed  white  metal  bearings. 

The  Cam  Shaft,  which  is  supported  by  six  bronze  bearings  in 
the  upper  half  of  the  crank  case  between  the  two  banks  of  cylin- 
ders, is  hollow  bored  throughout  and  the  cams  are  formed  inte- 
gral with  the  shaft. 

The  Gears  that  operate  the  cam  shaft,  magneto,  oil  and  water 
pumps  are  contained  in  an  oil  tight  casing  and  operate  in  an  oil 
bath. 

Valves  are  of  hardened  tungsten  steel,  mechanically  operated, 
and  are  of  generous  proportion.  They  are  operated  by  rocker 
arms,  one  for  each  valve,  off  the  cam  shaft.  A  system  of  double 
springs  reduces  the  stress  on  each  spring ;  a  large  diameter  spring 
returns  the  valve,  while  a  second  spring  at  the  cylinder  base 
handles  the  push  rod  linkage. 

The  Crank  Case  is  cast  from  an  aluminum  alloy  deeply  ribbed 
at  points  of  high  stress.  The  lower  half  contains  the  oil  sump, 
which  is  entirely  covered  by  an  oil  filtering  screen. 

Carburetion. — The  carburetor  is  the  Zenith  duplex  type.  It 
is  a  double  barrel  design  with  one  float  chamber  and  two  jets, 


m 


FlG.  76. — Side  and  End  View  Sturtevant  Aeroplane  Engine. 


FIG.  77.— Side  and  End  View  Curtiss  OXX3  Aeroplane  Engine. 


AERIAL    MOTORS.  127 

each  jet  supplying  one  bank  of  four  cylinders.  It  is  located 
at  the  rear  end  of  the  motor  beneath  the  level  of  the  engine  base, 
thus  permitting  of  gravity  feed.  It  is  connected  to  the  cylinders 
by  means  of  aluminum  manifolds,  having  integral  cast  water 
jackets. 

Ignition  is  by  two  eight  cylinder  waterproof  Bosch  or  Splitdorf 
magnetos  placed  face  to  face  between  the  two  banks  of  cylinders. 
Each  cylinder  is  provided  with  double  ignition  by  means  of  two 
spark  plugs  located  in  water  cooled  bosses  on  the  sides  of  the 
cylinder  heads. 

Lubrication  is  of  the  complete  forced  circulation  system,  oil 
being  supplied  to  every  bearing  "by  a  large  capacity  rotary  pump, 
which  is  gear  driven  from  the  cam  shaft. 

Starting  Crank. — The  engine  can  be  started  from  the  machine 
by  a  crank  handle  or  an  air  starter  can  be  readily  installed. 

3.  Horizontal    Opposed    Engines. 

The  Ashmusen  Motor,  Fig..  78,  is  of  the  horizontal  opposed- 
cylinder  type;  it  is  a  four-cycle,  air  cooled,  twelve  cylinder  en- 
gine, having  a  bore  of  3^4  inches,  stroke  of  4^2  inches,  and  de- 
velops 105  H.P.  at  1,800  revolutions  per  minute.  It  weighs  about 
360  pounds. 

It  is  equipped  with  two  improved  Ashmusen  carburetors  and 
double  manifolds.  Air  is  drawn  through  flutes  on  the  sides  of 
the  cylinders  to  the  manifolds,  thence  to  the  carburetors.  This 
system  accomplishes  the  double  purpose  of  cooling  the  cylinders 
and  heating  the  air  to  the  carburetor.  Delco  ignition  is  used. 
The  propeller  is  driven  from  the  cam  shaft  at  one-half  motor 
speed.  The  cylinders,  cylinder  heads  and  pistons  are  of  grey 
iron.  The  crank  shaft  is  a  heat  treated  nickel  steel  forging.  The 
crank  case  is  aluminum  alloy.  The  valves  are  tungsten  steel. 
Main  and  cam  shaft  bearings  are  of  the  ball  type.  Wrist  pin 
bearings  are  of  Parson's  metal.  A  compression  release  is  fitted 
to  hold  the  exhaust  valves  off  their  seats.  Perfect  balance,  min- 
imum vibration,  and  accessibility  are  claimed,  the  makers  stating 
that  it  is  possible  to  remove  all  cylinders  and  replace  them  in  45 
minutes. 


AERIAL    MOTORS. 


I29 


4.  Radial  Aeroplane  Engines. 

Radial  motors  are  designed  with  the  cylinders  disposed  radially 
about  the  center  line  of  the  shaft,  Fig.  79.  Valves  are  located  in 
the  cylinder  head.  Practically  all  radial  motors  are  air  cooled. 
The  radial  motor  can  be  more  perfectly  balanced  than  can  other 
types,  but  this  advantage  is  offset  by  the  higher  head  resistance 
offered  by  the  motor. 

The  Anzani  Motor  is  an  air  cooled  motor  built  in  banks  of 
three  or  five  cylinders,  being  rated  at  about  10  H.P.  per  cylinder 
at  about  1,200  revolutions.  Fig.  79  illustrates  the  100  H.P.  Anzani 


FIG.  79. — Anzani  Motor  with  Muffler. 

Motor.  It  is  built  in  two  banks  of  five  cylinders  each.  Fig.  80 
is  a  cross  section  of  the  60  H..P.  six  cylinder  motor,  with  one 
bank  of  cylinders  removed. 

The  Crank  Case  M  M  is  aluminum  alloy,  made  in  halves,  con- 
nected together  by  through  bolts  N  N.  These  bolts  also  serve  to 
attach  the  engine  to  the  aeroplane.  A  dirt  and  sediment  sump  is 
fitted  in  the  bottom  of  the  case. 


130  INTERNAL    COMBUSTION    ENGINE)    MANUAL. 

Cylinders  K  K  are  of  cast  iron,  with  cooling  ribs,  the  flat 
cylinder  tops  containing  the  inlet  and  exhaust  valve  seats.  The 
cylinders  are  slightly  offset.  They  are  attached  to  the  crank  case 
each  by  two  long  bolts  connected  to  the  through  crank  case  bolts 
at  the  inner  end  and  passing  through  bosses  on  the  cylinders  at  the 
outer  end,  as  shown  at  L.  These  through  bolts  take  the  longi- 
tudinal strains  due  to  the  explosions. 

Pistons  H  are  of  cast  iron,  ground  to  fit  and  provided  with 
stiffening  ribs  on  the  under  side  of  the  flat  crown.  There  are 
two  piston  rings.  The  wrist  pins  are  hollow,  of  nickel  steel, 
hardened  and  ground,  and  secured  in  the  piston  bosses  by  a  set 
screw  as  shown. 

Connecting  Rods  B  are  of  high  tensile  nickel  steel  of  H  section 
with  a  plain  bronze  bushed  wrist  pin  end.  The  crank  pin  end 
connection  is  shown  in  section  in  Fig.  80.  Each  connecting  rod 
ends  in  a  shoe  C.  The  three  shoes  of  each  bank  of  cylinders  bear 
on  a  cylindrical  bronze  sleeve  D  (made  in  halves),  which  em- 
braces the  crank  pin  and  rotates  thereon;  the  whole  is  held  to- 
gether by  two  bronze  collars  £.  £. 

Valves  are  of  nickel  steel  and  of  large  diameter.  The  inlet 
valves  are  spring  loaded  automatic  valves,  a  bad  feature  that  will 
probably  be  abandoned.  The  exhaust  valves  are  operated  through 
push  rods  and  rocker  arms  by  the  cam  U.  This  cam  is  made  in- 
tegral with  its  driving  pinion  V  which  runs  on  the  bronze  sleeve 
Y ;  it  is  driven  from  the  pinion  W  through  intermediate  gears. 

Carburetion. — A  Zenith  carburetor  is  used.  From  the  car- 
buretor the  mixture  goes  to  the  annular  chamber  P  surrounding 
the  rear  end  of  the  crank  case,  and  from  this  chamber  pipes  R 
lead  to  the  inlet  valves.  The  exhaust  can  be  discharged  directly 
to  the  atmosphere  at  S  or  a  collector  muffler  can  be  fitted,  Fig.  79. 

Ignition  is  by  high  tension  magneto  T,  gear  driven  from  the 
rear  end  of  the  crank  shaft.  Two  spark  plugs  are  fitted  to  each 
cylinder. 

Lubrication. — A  cam  operated  plunger  type  oil  pump  (not 
shown)  is  formed  on  the  crank  case  cover.  It  delivers  oil  at  A 
under  pressure,  and  oil  is  supplied  to  the  pistons,  wrist  pins,  and 
all  internal  parts  through  the  crank  shaft.  An  oil  fog  is  main- 
tained in  the  crank  case  when  the  engine  is  running. 


AERIAL    MOTORS. 


FIG.  80. —  Cross  Section  of  Anzani  Motor. 


132  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

5.  Rotary  Aeroplane  Motors. 

The  distinguishing  feature  of  a  rotary  motor  is  that  the  crank 
shaft  and  crank  are  stationary  and  the  cylinders  revolve  about 
the  shaft.  This  produces  the  same  relative  motion  of  pistons  to 
cylinders  as  though  the  cylinders  were  stationary  and  the  crank 
revolved.  From  Fig.  81,  showing  the  connections  between  the 
pistons  and  the  crank  shaft  in  a  rotary  engine,  it  is  obvious  that 
it  matters  not  which  is  the  revolving  member.  The  relative 
piston-cylinder  positions  will  be  the  same. 

The  rotary  motor  has  several  inherent  disadvantages.  The 
head  resistance  is  greater  than  in  a  stationary  motor.  It  is  esti- 


FIG.  81. 

mated  that  7%  to  9%  of  the  power  developed  is  expended  in 
overcoming  the  effect  of  the  whirling  cylinders.  Power  is  con- 
sumed in  driving  the  cylinders  about  the  shaft.  The  gyroscopic 
effect  of  the  whirling  cylinders  is  a  handicap  to  the  operator. 
The  lubricating  waste  is  large,  the  compression  is  low,  and  the 
engine  cannot  be  satisfactorily  muffled. 

The  crank  shaft  is  secured  to  the  aeroplane.  The  propeller  is 
made"  fast  to  the  front  of  the  cylinder  base  and  revolves  with  it. 
Fig.  82  shows  a  cross  section  of  the 

Gnome  Engine. — The  cylinders  are  made  of  forged  chrome 
ntekel  steel,  about  1/16  inch  thick  with  cooling  fins  on  the  out- 
side. They  are  secured  to  the  crank  case  by  a  lock  ring. 


AERIAL  MOTORS.  133 

The  crank  case  is  of  nickel  steel  in  the  form  of  a  hoop  having 
holes  bored  in  the  circumference  to  seat  the  cylinders. 

The  carburetor  is  in  the  rear  of  the  engine,  the  charge  passing 
through  the  hollow  shaft  to  the  crank  case. 

Automatic  inlet  valves  in  the  piston  heads  admit  the  charge  to 
the  cylinders. 

Exhaust  valves  in  the  cylinder  heads  are  operated  by  an  ar- 
rangement of  female  cam  plates  bolted  to  the  cylinder  base  and 
male  cam  plates  on  the  crank  shaft.  Motion  is  transmitted  to  the 
valves  by  push  rods. 


-Exhaust  Value 


Valve  Tappet 
Cooling  Flanges-Jfi^ 


Oil  Feed  Sight 
Qauge  Glasses 

X 


Engine  Base 


Oil  Pipes 
FIG.  82. — Cross  Section  of  Gnome  Motor. 


134  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

Ignition  is  by  high  tension  magneto  direct  to  spark  plugs,  via  a 
very  simple  distributor;  the  spark  is  advanced  automatically. 

Lubrication  is  by  forced  feed.  The  oil  pump  A,  Fig.  82,  forces 
oil  through  the  oil  sight  feed  gage  glasses  and  pipes  in  the  hollow 
crank  shaft  to  the  bearings  and  by  ducts  to  all  points  requiring 
lubrication. 

The  Gyro  Duplex  Motor,  Fig.  83. — This  is  an  American-built 
9  cylinder,  air-cooled  rotary  motor,  developing  100  H.P.  (nor- 
mal) at  1,130  R.P.M. ;  bore,  4^  inches;  stroke,  6  inches;  weight, 
270  pounds. 

Cylinders  are  turned  from  solid  billets  of  special  alloy  steel, 
with  cooling  fins  on  the  outside,  and  carefully  balanced  to  elimi- 
nate vibration. 

Pistons  are  of  the  best  grade  cast  iron,  fitted  with  oil  deflectors 
for  economy,  and  two  piston  rings  of  special  design. 

Connecting  rods  are  of  vanadium  steel  and  heat  treated.  The 
connecting  rod  assembly,  or  spider,  is  carefully  balanced. 

Crank  shaft  is  of  nickel  steel,  drilled  out  for  lightness,  and 
serves  as  a  gas  and  oil  passage  to  the  crank  case. 

Crank  case  is  of  vanadium  steel,  made  in  two  halves,  the  cylin- 
ders being  clamped  between  the  two  halves. 

Cam  valve  drive  is  of  the  Duplex  type  driven  from  a  differen- 
tial gear  train. 

Ignition  is  by  Bosch  high  tension  magneto  direct  to  spark  plug, 
via  a  simple  distributor. 

Carburetion  is  semi-automatic,  gasoline  being  fed  to  the  crank 
case  through  a  gear  driven  pump  and  a  spray  nozzle. 

Lubrication  is  automatic  and  absolutely  positive,  being  supplied 
by  a  gear  driven  displacement  pump  to  the  central  bearing  and 
from  there  through  ducts  to  all  points  of  friction. 

A  variable  compression  cam  allows  the  motor  to  start  readily 
and  to  run  idle  at  250  to  300  R.P.M.  There  are  no  inlet  valves, 
back  pressure  is  reduced,  back-firing  eliminated,  and  no  oil  waste 
occurs  through  the  piston  head. 


AEREAI,    MOTORS. 


135 


To  Duplex 
Cam 

FiG.  84. — Section  Through  Cylinder — Gyro  "Duplex"  Aeroplane  Motor. 


MOTORS.  137 

Operation,  Fig.  84. — The  inside  of  the  motor  is  bare  of  all  ac- 
cessories save  the  piston  P,  the  connecting  rods  R,  and  the  crank 
shaft.  The  main  exhaust  valve  D  is  located  on  the  cylinder  top 
and  is  operated  by  a  rod  and  cam.  This  cam  is  of  the  duplex 
type,  one  side  operating  the  main  exhaust,  the  other  the  slide  in- 
take mechanism  B,  C ;  the  latter  is  attached  to  the  outside  of  the 
cylinder  about  two  inches  above  the  end  of  the  power  stroke.  It 
is  readily  detachable. 

At  this  point  there  are  provided  auxiliary  exhaust  ports  A, 
through  which  the  main  pressure  of  the  nearly-spent  stroke  ex- 
hausts itself,  thereby  reducing  the  pressure  necessary  to  open  the 
main  exhaust  valve.  Outside  of  these  ports  is  a  cage,  B,  in  which 
a  small  hollow  slide,  C,  moves  with  a  stroke  of  about  one-half 
inch,  y  to  s;  this  stroke  depends  upon  the  shape  of  another  cam 
forming  a  twin  to  the  main  exhaust  cam. 

The  operation  is  as  follows:  When  the  power  stroke  reaches, 
the  auxiliary  ports  A  the  gases  escape  and  relieve  the  pressure  in 
the  cylinder.  The  piston  continues  lJ/£  inches,  to  the  end  of  the 
stroke,  and  then  returns  for  scavenging  the  burnt  gases  out 
through  the  main  exhaust  D;  the  piston  then  moves  down  for  the 
intake. 

The  exhaust  D  remains  open  until  just  before  the  piston  on  its 
intake  stroke  reaches  the  auxiliary  ports  A.  In  the  meantime 
the  small  intake  slide  C  has  moved  outward  to  z  and  the  auxiliary 
port  A  is  now  connected  through  the  cage  B  to  a  gas  conduit 
filled  with  fresh  mixture.  The  main  exhaust  has  closed  and  the 
piston  moves  lT/2  inches  farther  and  sucks  the  fuel  into  the  cylin- 
der. The  intake  slide  C  then  returns  to  its  original  position, 
while  the  piston  moves  outward  on  the  compression  stroke. 


CHAPTER  XII. 

THE  DIESEL  ENGINE. 

This  engine,  the  invention  of  the  late  Mr.  Rudolph  Diesel,  of 
Munich,  differs  in  its  cycle  from  all  previous  internal  combustion 
engines  in  compressing  a  full  charge  of  air  to  a  temperature  above 
the  ignition  temperature  of  the  fuel,  then  injecting  the  fuel  for  a 
certain  period  (variable  according  to  the  load)  into  this  highly 
heated  air  where  it  burns  with  limits  of  temperature  and  pressure 
under  perfect  control.  ATo  fuel  is  present  in  the  cylinder  during 
compression  (this  is  the  distinctive  Diesel  feature),  and  a  uniform 
combustion  takes  place  at  a  predetermined  temperature,  the  com- 
bustion line  being  represented  as  an  .isothermal. 

Classification. — Diesel  engines  are  broadly  classified  as  two 
cycle  and  four  cycle.  In  both  types  a  cylinder  full  of  air  at  about 
atmospheric  pressure  is  compressed  by  the  piston  until  at  the  top 
center  its  pressure  becomes  about  500  pounds  per  square  inch, 
and  its  consequent  temperature  about  1,000°  F.  At  this  instant  a 
small  quantity  of  oil  fuel  is  blown  into  the  very  hot  compressed 
air  by  means  of  a  jet  of  air  at  a  still  higher  pressure. 

Operation. — The  fuel  valve  is  so  designed  that  the  oil  is  broken 
into  a  fine  spray  and  admission  lasts  only  about  one-tenth  of  the 
downward  stroke.  During  this  short  time  much  of  the  oil  is 
burned  in  the  hot  air.  The  heat  generated  by  the  combustion 
raises  the  temperature  greatly,  and  consequently  must  increase 
either  or  both  the  pressure  and  the  volume  occupied.  As  a  mat- 
ter of  fact,  the  aim  is  to  have  combustion  proceed  at  the  critical 
rate  which  would  permit  the  increase  of  volume  occupied,  due  to 
the  motion  of  the  piston  and  the  increased  temperature,  to  be  so 
balanced  that  the  pressure  will  remain  constant  throughout  com- 
bustion. 

After  combustion  is  complete,  expansion  of  the  hot  gas  will 
still  further  push  the  piston  down,  and  the  pressure  will  decrease 


THE:    DIESEL    ENGINE.  139 

rapidly.  The  temperature  will  also  fall  rapidly,  mainly  from 
conversion  of  part  of  the  heat  into  work,  but  also  partly  by  the 
radiation  of  some  of  the  heat  through  the  cylinder  walls  to  the 
surrounding  cooling  water. 

The  Maximum  Temperatures  actually  attained  in  the  cylinder 
are  very  high,  approximating  in  some  cases  to  nearly  3,000°  F. 
It  is  these  excessively  high  temperatures  that  occasion  some  of 
the  Diesel  engine  difficulties.  It  is  necessary  to  keep  the  rubbing 
surfaces  of  the  metal  which  are  exposed  to  the  hot  gases  suffi- 
ciently cool  to  permit  them  to  retain  their  lubrication,  and  it  is 
also  necessary  to  prevent  all  metal  which  comes  into  contact  with 
the  heat  from  becoming  so  overheated  as  to  damage  its  strain- 
resisting  properties. 

These  extremely  high  temperatures  also  complicate  the  ques- 
tions of  expansion  of  the  cylinder  materials  and  hence  the  foundry 
work  involved.  The  consequent  high  pressures  cause  unusually 
high  tension  stresses  in  the  columns,  tie  rods,  cylinders,  etc.,  and 
make  for  heavy  vibrations. 

Design  Problems. — The  above  engineering  problems  were  new 
to  prime  movers  and  had  to  be  solved  before  a  successful  Diesel 
engine  could  be  produced.  Adequate  cooling  systems  have  been 
devised  to  handle  the  high  temperatures,  heavy  columns  and  tie 
rods  to  meet  the  high  tension  stresses  have  overcome  the  vibra- 
tion. The  expansion  problems  had  been  solved,  to  a  limited  ex- 
tent, in  the  foundries. 

While  it  may  be  admitted  that  the  early  claims  were  much  too 
sanguine,  and  that  the  glowing  anticipations  of  the  early  enthu- 
siasts have  not  as  yet  been  entirely  fulfilled,  yet  there  is  no  doubt 
that  the  development  of  this  engine  thus  far  justifies  a  wonderful 
outlook  for  its  future. 

The  Reasons  for  the  Success  of  certain  designs  are  worthy  of 
study  as  marking  the  trail  of  future  progress.  Over-ambition  led 
to  excessive  increase  in  sizes  of  the  units  without  first  over- 
coming the  difficulties  involved.  Also,  attempts  were  made  to 
convert  the  land  engine  to  marine  use  without  first  adapting  it  to 
this  new  work.  In  the  successful  engines  increase  of  power  has 


140  INTERNAL    COMBUST-ION    ENGINE    MANUAL. 

generally  been  attained  by  multiplying  the  units  instead  of  in- 
definitely increasing  the  size  of  the  unit;  price  has  not  been  cut; 
weight  has  not  been  sacrificed ;  simplicity  has  not  been  forced. 

The  Well  Known  Advantages  of  the  oil  engine  for  naval  use, 
namely,  the  saving  in  space,  weight,  fuel  and  personnel,  and  the 
possibility  of  getting  underway  quickly,  has  repeatedly  caused 
predictions  that  the  oil  engine  must  be  developed  for  larger 
powers.  The  largest  American  built  marine  Diesel  installation 
is  the  5,000  H.P.  plant  on  the  Naval  collier  Mauniee. 

Cycles. — The  foregoing  remarks  apply  to  all  types  of  Diesel 
engines.  In  the  four-stroke  cycle  engine  the  exhaust  takes  place 
through  valves  in  the  cylinder  covers,  the  gases  being  pushed  out 
by  the  piston  on  its  return  stroke.  During  the  next  stroke  fresh 
air  is  drawn  into  the  cylinder  through  other  valves  also  situated 
in  the  cylinder  cover.  It  is  compressed  during  the  third  stroke, 
and  the  fuel  is  then  admitted  in  the  same  manner  at  the  com- 
mencement of  the  next  stroke,  as  in  the  two-stroke  cycle  type. 

In  the  case  of  the  two-stroke  cycle  engine,  just  before  the 
completion  of  the  expansion  stroke  the  piston  uncovers  ports  in 
the  lower  part  of  the  cylinder  walls  leading  into  an  exhaust  pass- 
age, and  a  considerable  portion  of  the  hot  gas  escapes,  the  pressure 
falling  to  about  that  of  the  atmosphere.  Then  in  some  designs 
valves  in  the  cylinder  cover  are  opened  and  fresh  air  supplied  by 
the  scavenger  pump  at  a  pressure  of  about  4  pounds  per  square 
inch  blows  out  the  remainder  of  the  burnt  gas,  leaving  the  cylinder 
full  of  fresh  air  ready  to  be  compressed  by  the  return  stroke  of 
the  piston ;  in  other  designs  the  exhaust  ports  are  placed  on  one 
side  only  of  the  lower  end  of  the  cylinder,  and  on  the  other 
side  similar  ports,  also  opened  by  the  travel  of  the  piston,  but  at 
a  somewhat  later  instant,  admit  the  scavenging  air.  In  these 
latter  cases  the  tops  of  the  pistons  are  curved  to  direct  the 
entering  air  upwards,  and  it  is  claimed  that  the  scavenging  air 
travels  right  to  the  top  of  the  cylinder  and  entirely  displaces  the 
burnt  gas.  In  these  latter  designs  the  scavenger  valves  and  the 
gear  for  working  them  are  dispensed  with,  and  consequently  the 
engines  are  to  some  extent  simplified. 


THE;    DIESEL    ENGINE.  141 

It  will  be  observed  that  in  the  two  cycle  engine  there  is  one 
impulse  in  each  cylinder  every  revolution,  while  in  the  four  cycle 
there  is  only  one  impulse  per  two  revolutions,  so  that  with  the' 
same  diameter  of  cylinder  and  the  same  piston  speed  double  the 
number  of  cylinders  have  to  be  used  with  a  four  cycle  compared 
with  a  two  cycle  engine  of  the  same  power,  if  the  same  mean 
pressures  are  maintained.  In  both  types  a  considerable  part  of 
the  energy  exerted  during  the  impulse  stroke  is  used  up  in  the 
following  compression  stroke.  Also  in  the  two  cycle  large  scav- 
enger air  pumps  have  to  be  provided,  having  an  aggregate  ca- 
pacity greater  than  that  of  the  whole  of  the  cylinders,  and  con- 
siderable power  is  expended  in  working  these  pumps,  and  this 
must  be  taken  off  the  effective  power  of  the  engine.  On  the  other 
hand,  the  four  cycle  engine  has  the  engine  friction  (pistons, 
guides,  shafts,  etc.)  during  twice  the  number  of  strokes  as  com- 
pared with  the  two  cycle,  and  it  also  has  to  be  provided  with 
exhaust  valves  and  gear  to  work  them,  which  are  not  required  in 
two  cycle  engines.  On  the  whole  there  is  no  doubt  that  while  the 
indicated  power  obtained  from  a  stated  quantity  of  oil  is  about 
the  same  in  both  types  of  engines  working  under  similar  condi- 
tions of  compression  and  fuel  supply,  the  four  cycle  engine  is 
somewhat  more  efficient  than  the  other,  in  that  a  larger  propor- 
tion of  the  power  exerted  on  the  pistons  is  transmitted  to  the 
screw,  owing  to  the  fact  that  no  power  is  expended  in  supplying 
scavenging  air. 

The  Four  Cycle  Diesel. 

This  type,  commonly  called  the  American  Diesel  Engine,  re- 
ceived most  of  its  early  development  in  this  country.  It  is  a 
vertical,  four  cycle,  single  acting,  stationary  engine,  Fig.  85. 

Fuel  is  pumped  to  the  fuel  chamber  by  a  fuel  pump.  A  two 
stage  compressor,  generally  driven  from  the  main  shaft,  serves  to 
compress  air  to  about  800  pounds  pressure.  This  air  is  cooled 
before  use,  and  is  used  only  to  inject  fuel  from  the  fuel  chamber 
to  the  cylinder,  and  to  charge  an  air  tank  for  starting  the  engine 
when  cold.  An  extremely  sensitive  governor  controls  the  quan- 


142 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


FIG.  85. — Diesel  Engine,  Four  Cycle. 


THE    DIESEL    ENGINE. 


143 


tity  of  fuel  injected  each  stroke.  So  fine  is  this  regulation  that 
the  engine  can  operate  alternating  current  generators  in  parallel 
without  difficulty. 

,  The  fuel  used  at  half  load  rarely  exceeds  55%  of  that  used  at 
full  load,  so  the  fuel  consumption  is  nearly  proportional  to  the 
work  done.  This  very  marked  contrast  to  the  performance  of 
other  types  of  engines  is  the  result  of  features  inherent  in  the 
Diesel  cycle  alone,  and  is  due  to  direct  regulation  of  the  fuel 
supply  by  the  governor. 

CYCLE  OF  OPERATIONS. 

As  stated  above,  the  fuel  is  not  compressed,  only  air  being  in 
the  cylinder  during  this  stage  of  the  cycle,  hence  pre-ignition  is 
impossible.  The  clearance  is  very  small.  The  complete  cycle  is 
as  follows : 

1.  Aspiration  Stroke. — The  piston  moves  to  the  bottom  of  the 
cylinder  and  during  this  stroke  the  air  admission  valve  opens  and 
allows  the  cylinder  to  fill  with  air  at  atmospheric  pressure. 

2.  Compression  Stroke. — The  piston  moves  to  the  upper  end 
of  the  cylinder,  the  admission  valve  closes,  and  the  air  in  the 
cylinder  is  compressed  to  500  pounds  per  square  inch,  at  which 
pressure  its  temperature  is  sufficient  to  ignite  any  form  of  petro- 
leum   (crude   or   refined)    spontaneously.      No  valves   are  open 
during  this  stroke  and  there  is  nothing  in  the  cylinder  but  pure 
air. 

3.  Expansion  Stroke. — When  the  piston  has  reached  the  top 
of  the  compression  stroke  and  the  crank  is  just  crossing  the  dead 
center,  a  small  needle  valve,  Fig.  86,  opens  and  a  charge  of  liquid 
fuel  mixed  with  compressed  air  is  blown  into  the  highly  heated 
air  already  in  the  cylinder.     Ignition  takes  places  as  the   fuel 
comes  in  contact  with  this  hot  air.    The  fuel  valve,  together  with 
the  air  and  exhaust  valves,  is  placed  at  the  side  of  the  cylinder  at 
the  top  end,  and  all  valves  open  into  the  same  space.    The  quan- 
tity of  fuel  is  not  all  blown  in  at  once;  instead,  fuel  injection  is 
maintained  for  a  period  equal  to  10%  of  the  downward  stroke  of 
the  piston.     It  would  be  impossible  to  maintain  this  long  period 


144.  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

of  admission  if  fuel  alone  were  injected,  but  the  compressed  air, 
which  is  blown  in  with  the  fuel  and  which  is  thoroughly  mixed 
with  the  fuel  by  the  perforated  washers  that  surround  the  needle 
valve,  increases  the  volume  and  thus  gives  a  quantity  whose  injec- 
tion can  be  controlled.  The  compressed  air  referred  to  is  that 
supplied  by  the  two  stage  compressor  at  800  pounds  pressure  and 
cooled  before  introduction  into  the  fuel  valve. 

After  the  needle  valve  closes,  the  hot  gases  expand  until  the 
piston  has  traveled  90%  of  its  stroke,  when  the  exhaust  opens  to 
relieve  the  pressure.  The  pressure  at  opening  "of  the  exhaust 
valve  for  normal  load  is  generally  35  pounds  per  square  inch,  and 
the  temperature  about  700°  F.  The  pressure  in  the  cylinder  is 
not  due  to  the  expansion  of  gases  of  combustion  alone,  for  there 
is  a  large  excess  of  air  present  and  the  high  heat  attained  is 
sufficient  to  expand  this  excess  air  also. 

4.  Exhaust  Stroke. — This  fourth  and  last  stroke  of  the  cycle 
takes  place  on  the  upward  stroke.  The  exhaust  valve  is  open  and 
the  hot  gases  are  forced  out  by  the  piston.  When  the  piston 
reaches  the  top  center,  the  exhaust  valve  closes,  the  admission 
valve  begins  to  open  and  the  cycle  is  repeated. 

The  engine  is  water  cooled  and  the  fuel  and  exhaust  valves  are 
operated  as  shown  in  Fig.  85.  A  is  a  cam  on  the  countershaft,  B 
is  the  cross  rod  with  a  roller  bearing  on  the  cam  A,  and  C  is  the 
push  rod  that  actuates  the  valve  stem.  Splash  lubrication  is  used 
for  the  cylinder,  and  the  main  bearings  are  lubricated  by  an  oil 
ring  and  an  oil  chamber.  The  fuel  valve  is  made  of  nickel  steel 
to  prevent  abrasion  by  the  petroleum.  The  piston  is  of  the  long 
trunk  type,  being  approximately  2  1/3  times  the  diameter  in 
length,  tapering  1/32  inch,  and  provided  with  four  snap  rings. 

Governor. — The  governor  is  connected  to  a  by-pass  at  the 
fuel  pump.  The  pump  runs  at  constant  speed.  If  the  load  is 
light  and  the  fuel  requirement  is  low,  the  governor  holds  the  by- 
pass valve  open  and  allows  a  large  amount  of  oil  to  return  to  the 
suction  side  of  the  pump ;  when  the  load  increases,  more  oil  is  re- 
quired ;  the  governor  holds  the  by-pass  open  for  a  shorter  period, 
less  oil  goes  back  to  the  pump  suction  and  more  goes  to  the 
engine. 


THE    DIESEL,    ENGINE. 


Valve  Group. — The  group  consists  of  the  air  and  exhaust 
valves,  which  require  no  special  consideration,  and  the  fuel  valve. 
This  last  consists  of  a  needle  valve  A  (Fig.  86),  which  is  cam 
actuated  from  the  cam  A  (Fig.  85)  through  the  bell  crank  lever  D 
(Fig.  86),  always  opening  during  the  same  period  each  cycle. 


FIG.  86. — Valve  Group,  Diesel  Engine. 

Fuel  is  introduced  through  the  pipe  B,  the  amount  being  regulated 
by  the  governor  for  each  cycle  as  stated  above.  Compressed  air, 
which  is  previously  cooled,  enters  at  C,  and  the  perforated 
washers  H  serve  to  mix  this  air  with  the  fuel.  When  the  needle 
valve  is  opened  the  compressed  air  blows  the  fuel  into  the 
cylinder. 

The  exhaust  valve  is  cam  actuated  from  the  same  countershaft 
10 


146  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

(Fig.  85)  as  is  the  fuel  valve.  In  the  engine  shown  here  the  air 
valve  is  an  ordinary  spring  loaded  valve  which  automatically 
opens  on  the  suction  stroke  and  closes  on  the  compression  stroke. 
In  larger  Diesel  engines  this  valve  is  cam  actuated  in  the  same 
manner  as  the  fuel  and  exhaust  valves. 

Limits  of  Power. — The  power  of  the  four  cycle  engine  is  lim- 
ited by  difficulties  of  dealing  with  the  exhaust,  unless  auxiliary 
exhaust  ports  (similar  to  the  two  cycle  exhaust  ports  described 
later)  be  introduced.  Auxiliary  exhaust  ports  have  been  applied 
to  fast  running  four  cycle  engines  to  permit  the  escape  of  the  high 
temperature  gases  before  the  cylinder  head  exhaust  valve  opens. 
This  method  of  exhaust  with  both  ports  and  valves  decreases 
the  mean  effective  pressure  and  decreases  the  efficiency  of  suction, 
since  the  ports  are  open  at  the  beginning  of  the  suction  stroke  and 
the  quality  of  the  charge  is  thus  affected.  The  gain  in  weight  and 
space  occupied  by  the  two  cycle  engine  is  not  great,  especially 
since  the  fuel  consumption  is  about  10%  greater  in  this  type,  but 
notwithstanding  this,  to  obtain  the  maximum  mean  effective  pres- 
sure per  revolution  the  two  cycle  engine  has  been  generally 
adopted  for  marine  use. 

The  Two  Cycle  Diesel. 

There  are  two  general  types  of  the  two  cycle  Diesel  engine  in 
use  in  the  U.  S.  Navy.  They  differ  in  the  method  of  compressing 
and  supplying  the  scavenging  air.  The  Nurnberg  engine  com- 
presses the  scavenging  air  by  means  of  a  scavenger  cylinder  which 
is  under  and  an  integral  part  of  the  working  cylinder  and  supplies 
this  air  through  air  valves  in  the  cylinder  head.  The  Sulzer 
engine  compresses  the  scavenging  air  by  a  separate  air  compressor 
which  is  operated  by  the  engine  main  shaft,  and  supplies  this  air 
through  scavenger  ports  in  the  bottom  of  the  cylinder  side. 

Each  engine  has  an  air  compressor  driven  by  the  engine  main 
shaft  to  supply  air  for  fuel  injection,  starting  and  reversing.  In 
the  following  descriptions  of  these  two  engines  care  must  be  exer- 
cised to  distinguish  between  the  compressed  air  for  scavenging 
and  that  for  fuel  injection.  The  former  is  maintained  at  only 
about  10  pounds  pressure,  and  is  supplied  differently  in  the  two 
engines.  The  latter,  that  for  fuel  injection  and  starting,  is  main- 
tained at  about  800  pounds  pressure  and  is  supplied  in  a  similar 
manner  in  both  engines. 


THE    DIESEL    ENGINE.  147 

The   Nurnberg    Engine. 

The  following  description  is  that  of  a  450  horse-power  Nurn- 
berg Type  Engine,  as  built  by  the  New  London  Ship  and  Engine 
Co.  for  our  submarines.  The  engine  has  six  cylinders,  with  one 
two-stage  air  compressor  at  the  forward  end.  The  piston,  Fig. 
89,  is  in  steps,  the  upper  or  smaller  diameter  being  the  working 
piston  and  the  lower  or  larger  diameter  being  the  scavenger 
piston.  The  area  of  the  annular  part  of  the  scavenger  piston  is 
about  1.4  times  the  area  of  the  working  piston,  and  maintains 
about  9  pounds  pressure  in  the  scavenger  receiver.  The  space 
around  the  scavenger  cylinder  in  the  housing  (5),  Fig.  87,  is  used 
as  a  scavenger  receiver,  F. 

The  Cycle. — Assuming  in  Fig.  87  that  the  piston  has  just  ar- 
rived at  the  top  of  its  stroke,  and  consequently  the  cylinder  is  full 
of  air  compressed  to  about  500  pounds,  then  the  cycle  is  as  fol- 
lows :  On  the  down  stroke  the  fuel  valve  shown  on  top  of  the 
cylinder  at  the  left  opens  for  about  1/10  of  the  stroke  and  fuel  is 
injected  during  this  period.  The  compressed  air  present  in  the 
cylinder  is  of  sufficiently  high  temperature  to  ignite  this  fuel  and 
combustion  takes  place  during  this  period.  After  the  piston  has 
moved  downward  about  1/10  of  the  stroke  the  fuel  valve  closes,, 
and  expansion  continues  to  nearly  the  end  of  the  stroke.  Near 
the  bottom  of  the  stroke  the  piston  uncovers  exhaust  ports  in 
the  cylinder  wall  (not  shown  in  the  figure)  which  communicate 
with  the  exhaust  pipe  (1).  Simultaneously  the  scavenger  valve, 
shown  on  top  of  the  cylinder  at  the  right,  opens  and  scavenger 
air  at  about  10  pounds  pressure  is  introduced  to  the  cylinder, 
blowing  out  the  exhaust  gases.  This  leaves  the  cylinder  full  of 
fresh  air. 

The  piston,  on  its  return  stroke,  first  covers  the  exhaust  ports 
(not  shown)  in  the  cylinder  side,  and  then  compresses  the  air 
present  in  the  cylinder  to  about  500  pounds  pressure.  This 
completes  the  cycle. 

Scavenging. — During  the  down  stroke  of  the  piston  air  is 
drawn  through  the  scavenger  suction  valves  (2),  on  the  left  of 


148 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 

•CAMSHAFT 


PLATELS 
HANDHOLE: 


&E  PPL  ATE 

BAFFLE  PLATCS 
GUARD  PLATES 

FIG.  87. — Cross  Section,  Nurnberg  Engine. 


THE;  DIESEL  ENGINE:.  149 

the  cylinder,  through  ports  (not  shown)  in  the  scavenger  cylinder 
side.  This  is  just  below  the  working  cylinder.  On  the  up  stroke 
this  air  is  compressed  to  about  10  pounds  pressure  and  discharged 
through  the  spring  loaded  scavenger  discharge  valves  (4)  to  the 
annular  casing  formed  by  the  housing  (5).  This  is  the  scavenger 
receiver,  F.  The  pressure  of  the  scavenging  air  is  regulated  by 
the  scavenger  discharge  valves. 

The  scavenger  receiver,  F,  opens  to  all  scavenger  cylinders  and 
merely  acts  as  a  reservoir,  and  no  scavenger  cylinder  scavenges 
its  own  working  cylinder.  The  scavenging  air  is  led  through  a 
pipe,  /,  to  the  scavenger  valve,  and  when  that  opens  the  air  enters 
the  cylinder  and  blows  out  the  exhaust  gases,  the  exhaust  ports 
being  uncovered  during  this  period.  As  the  scavenging  is  done 
with  air  and  not  with  the  fuel  mixture  as  with  the  ordinary  two 
cycle  gasoline  engine,  complete  scavenging  and  thus  higher  effi- 
ciencies can  be  obtained.  Besides,  the  scavenger  valve  can  be  put 
where  scavenging  can  best  be  effected.  Also,  while  the  actual 
volume  of  air  is  considerably  less  than  the  volume  of  the  cylinder, 
the  fact  that  this  air  is  under  9  pounds  pressure  when  the  exhaust 
ports  are  closed  gives  this  engine  a  volumetric  efficiency  very 
close  to  that  of  the  four  cycle  engine,  which  has  not  a  greater 
pressure  at  the  same  part  of  the  stroke. 

Fuel  System. — Air  for  fuel  injection  is  supplied  by  the  air 
compressor,  Fig.  90,  to  accumulators  at  about  800  pounds  pres- 
sure. It  acts  at  the  fuel  valve  in  a  manner  similar  to  that  de- 
scribed under  the  four  cycle  Diesel  engine. 

There  is  a  separate  fuel-feed  pump  for  each  cylinder,  which 
takes  its  motion  from  an  eccentric  on  the  forward  end  of  the 
crank  shaft,  Fig.  88.  The  pumps  and  valves  are  together  at  the 
forward  end  of  the  engine,  and  discharge  through  small  copper 
pipes  into  the  spray  valves.  The  fuel  control  is  ingenious.  The 
plungers  of  the  fuel  feed  pump  (1),  Fig.  88,  run  at  a  constant 
stroke  and  discharge  through  spring  loaded  valves  (2),  into  the 
pipe  line  (3),  to  the  spray  valve.  The  suction  valve  (4)  also  acts 
as  a  regurgitating  valve  in  connection  with  the  plunger  which,  H 
open,  allows  the  oil  to  return  to  the  suction  side  of  the  pump.  The 


150 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


FIG.  88. — Fuel  Pump,  Nurnberg  Engine. 


THE)    DIESEL    ENGINE.  151 

amount  of  fuel  at  each  revolution  is  governed  by  the  length  of 
time  the  regurgitating  or  suction  valve  is  open.  If  the  regurgi- 
tating or  suction  valve  is  open  during  the  entire  revolution  of  the 
engine  no  fuel  will  go  into  the  engine.  This  is  accomplished  with 
a  driving  plate  (5),  which  governs  the  stroke  of  the  suction  valve 
and  in  this  manner  regulates  the  opening.  Fuel  oil  control  plate 
(6)  governs  the  position  of  the  driving  plate  (5).  As  the  fuel 
oil  control  plate  revolves  around  D  as  a  center,  the  center  C> 
about  which  driving  plate  (5)  oscillates,  moves  up  or  down.  As 
the  eccentric  rod  (?)  moves  up  and  down,  the  driving  plate  oscil- 
lates back  and  forth,  making  suction  valve  tappets  (8)  move  up 
and  down.  At  the  same  time  plunger  drive  lever  (9)  oscillates 
and  drives  plungers  (1)  up  and  down  a  constant  stroke.  As  the 
center  C  of  the  driving  plate  (5)  moves  down  the  arc  through 
which  tappet  shaft  lever  (10)  oscillates  will  move  toward  the 
center,  suction  valve  tappet  (8)  will  oscillate  lower  down,  and  the 
suction  valve  will  be  closed  during  a  longer  portion  of  the  stroke. 
As  C  moves  up,  the  tappet  (8)  will  oscillate  higher  up  and  keep 
the  suction  valve  open  during  a  greater  portion  of  the  stroke. 
While  suction  valve  (4)  is  open,  the  fuel  will  go  back  to  the  suc- 
tion line.  When  it  is  closed  the  oil  must  go  on  through  the  dis- 
charge valve  (2).  Consequently,  the  amount  of  fuel  discharged 
is  governed  by  the  length  of  time  the  suction  valve  is  open,  and 
this  in  turn  is  governed  by  the  position  of  center  C  of  the  driving 
plate.  The  governing  is  done  with  the  same  device.  That  is,  a 
ball  governor  (11)  on  the  cam  shaft  is  attached  through  levers 
(12,  13,  14)  to  fuel  regulating  device,  and  automatically  regulates 
the  opening  of  the  regurgitating  valve  in  the  same  manner  as  the 
fuel  control  plate  (6),  and  thus  governs  the  engine. 

Cooling  and  Lubrication. — The  working  and  scavenger  cylin- 
ders are  of  cast  iron,  but  for  lightness  the  housing  and  bedplates 
are  of  bronze.  Fig.  87  shows  that  the  scavenging  and  working 
cylinders  are  separate  castings  in  this  type  of  engine.  The  work- 
ing cylinder  (6)  is  water  jacketed,  as  is  the  exhaust  pipe  (1). 
The  air  starting,  spray,  and  scavenging  valves  are  not  jacketed. 


H 


FIG.  89.— Piston  of  Nurnberg  Engine. 


THE    DIESEL    ENGINE.  153 

The  piston  head  A,  Fig.  89,  is  oil  cooled.  The  oil  from  the 
wrist  pin  D  enters  a  hole  H  inside  the  piston,  flows  through  the 
head,  and  out  through  another  hole  F  on  the  opposite  side  of  the 
piston,  through  a  pipe  G  that  is  led  clear  of  the  wrist  pin  and  into 
the  crank  pit.  The  piston  is  made  in  two  sections.  Lower  section 
B  includes  the  body  of  the  working  piston  and  the  whole  of  the 
scavenging  piston,  while  the  upper  section  A  is  the  piston  head. 
This  construction  was  adopted  because  of  the  trouble  experienced 
with  the  core  plugs  in  the  top  of  the  piston  where  the  single 
casting  type  had  been  used.  After  a  certain  length  of  time  these 
core  plugs  would  come  out,  in  spite  of  all  precautions  taken  with 
their  installation,  and  cause  considerable  damage.  With  the  two- 
section  type  the  holding-down  bolts  are  in  recesses  in  the  side, 
and  never  come  into  contact  with  the  hot  gases,  and,  as  the  top 
has  no  holes  of  any  description,  there  is  now  no  trouble  with  core 
plugs  loosening.  The  upper  section  is  large  enough  to  take  all  of 
the  piston  rings.  The  wrist  pin  D  is  secured  in  the  scavenging 
piston  and  thus  is  not  exposed  to  the  heat  of  the  working  cylin- 
der. This  is  a  great  advantage  in  that  it  is  not  difficult  to  keep 
the  wrist  pin  bearings  cool. 

The  circulating  water  is  pumped  through  reciprocating  pumps 
on  the  forward  end  of  the  engine  geared  down  from  the  main 
shaft  to  4/9  revolutions  of  the  main  engine.  There  is  also  a  fuel 
pump  for  pumping  fuel  into  the  suction  of  the  fuel  feed  pumps 
described  above.  This  is  run  from  the  same  crosshead  from 
which  are  run  the  circulating  pumps.  All  the  handling  gear 
pumps,  etc.,  are  on  the  forward  end  of  the  engine.  The  lubricat- 
ing oil  pump  is  also  run  from  this  crosshead.  The  cylinder  lubri- 
cating oil  is  forced  under  pressure  by  a  special  lubricating  mani- 
fold run  from  the  vertical  cam  shaft  by  spiral  gearing  on  the 
after  end  of  the  engine. 

Starting  and  Reversing. — The  fuel,  scavenger,  and  starting 
valves  are  all  operated  by  levers  from  a  cam  shaft.  This  cam 
shaft  is  run  from  the  main  shaft  by  means  of  spiral  gearing  and 
vertical  shaft.  On  the  cam  shaft  are  the  spray  cams,  the  scaven- 
ger cams,  and  the  air  starting  cams.  The  reversing  is  accom- 


154 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


OISCHARGE    PIPE 
2V    5TAGE   CYLIN&EK  HEAD 


ITF 

AIR  COOLEK 


GUARD  PLATES 

FIG.  90. — Compressor,  Nurnberg  Engine. 


THE    DIESEL    ENGINE.  155 

plished  with  compressed  air.  The  vertical  shaft  has  a  special 
coupling  with  a  30°  blank.  On  reversing,  the  upper  section  re- 
mains stationary  till  the  lower  section  has  turned  through  30° 
when  all  cams  are  then  in  position  for  motion  in  the  opposite 
direction.  For  example:  The  spray  valve  begins  to  open  when 
the  crank  is  2T/20  in  advance  of  the  top  center  and  closes  when 
the  crank  is  32^°  beyond  the  top  center.  This  gives  an  opening 
of  the  spray  valve  through  35°.  Now  by  shifting  the  cam  shaft 
back  30°  by  means  of  this  clutch,  the  spray  valve  will  begin  to 
open  %y-2  °  on  the  opposite  side  and  remain  open  beyond  the  stroke 
32^2°  in  the  opposite  direction,  thus  reversing  the  functions  of 
the  spray.  The  scavenging  cams  are  reversed  by  the  same  action 
of  the  clutch  and  cam  shaft. 

The  reversing  is  accomplished  by  separate  cams  and  reversing 
valve,  or  air  starting  valve,  which  is  the  same  for  either  direction. 
This  air  starting  valve  is  in  the  cylinder  head.  It  is  not  shown 
in  Fig.  87. 


156 


INTERNAL    COMBUSTION    ENGINE    MANUAL. 


THE  DIESEL  ENGINE;.  157 

The  Sulzer  Engine. 

The  following  is  a  description  of  the  engines  of  the  Monte 
Penedo,  a  4,000-ton  German  steamer.  Her  engines  were  built  by 
the  Messrs.  Sulzer  Brothers,  of  Winterthur.  They  are  each  of 
850  B.  H.  P.  at  160  revolutions  per  minute,  four  cylinder,  single 
acting,  two  cycle,  directly  reversible  by  compressed  air.  The  four 
cylinders  are  coupled  in  pairs  by  the  scavenger  receivers  and  ex- 
haust connections. 

The  Compressor. — On  the  forward  end  of  each  engine  is  a 
three  stage  air  compressor,  driven  by  a  fifth  crank  on  the  main 
shaft.  This  compressor,  Fig.  92,  serves  the  double  duty  of  sup- 
plying air  at  high  pressure  for  fuel  injection  and  starting,  and  at 
low  pressure  for  scavenging.  On  the  completion  of  the  expan- 
sion or  working  stroke  (at  the  pistons'  lower  dead  center)  the 
cylinders  are  scavenged  and  filled  with  pure  air  from  this  com- 
pressor. 

In  the  air  compressor,  Fig.  92,  the  upper  cylinder  A  is  a  double 
acting  pump  which  supplies  low  pressure  scavenging  air.  This  air 
is  distributed  by  valves  driven  by  eccentrics  at  the  end  of  the 
main  shaft  Z,  Fig.  91.  From  the  compressor  the  scavenging  air 
travels  through  the  pipe  B,  Figs.  91  and  92,  to  the  receiver  C, 
Figs.  91  and  93,  thence  to  the  main  engine  cylinder  via  the  scav- 
enging ports  D,  Fig.  93. 

High  pressure  air  at  955  pounds  pressure,  for  fuel  injection 
and  starting,  is  also  supplied  by  this  compressor.  From  Fig.  92 
it  is  seen  that  the  first  stage  of  the  compressor  b  is  placed  directly 
below  the  scavenger  pump.  The  pumps  c  and  d,  forming  the 
second  and  third  stages,  respectively,  are  driven  from  the  first 
stage  piston  rod  by  the  rocking  lever  /  and  the  links  g  and  e.  This 
high  pressure  air  is  stored  in  four  groups  of  steel  receivers  or 
accumulators. 

The  compressors  are  water  cooled  and  are  provided  with  auto- 
matic valves,  so  that  no  special  reversing  gear  is  required. 

Fuel  System. — Oil  is  supplied  from  a  tank  in  each  engine 
room  to  the  main  fuel  oil  line.  Fuel  oil  is  supplied  to  all  fuel 
valves  of  the  engine  by  a  fuel  oil  pump  driven  fromj  the  main 
engine  by  a  rocking  beam.  A  constant  supply  of  oil  is  thus  main- 


FIG.  92.— Compressor,  Sulzer  Engine. 


THE    DIESEL    ENGINE.  159 

tained  at  the  fuel  valve.  The  amount  of  fuel  injected,  hence  the 
speed,  is  regulated  by  a  governor  which  acts  directly  on  the  fuel 
valve.  The  method  of  fuel  injection  at  the  fuel  valve  is  similar  to 
that  previously  described. 

Lubrication. — Each  engine  is  fitted  with  forced  lubrication, 
supplied  by  an  oil  circulation  pump,  driven  by  a  rocking  beam 
from  the  main  engine,  the  installation  comprising  an  oil  cooler, 
with  filters,  pressure  gages,  controlling  devices,  and  the  necessary 
oil  piping  to  every  part  requiring  lubrication.  The  oil  filters 
can  be  examined  and  cleaned  while  the  engine  is  running.  The 
oil  is  delivered  to  all  the  bearings  and  slide  paths,  and  it  collects 
in  the  base  plate,  whence  it  is  drawn  up  by  the  pump.  The 
working  cylinders  and  air  pumps  are  lubricated  by  small  separate 
oil  pumps. 

Cooling. — The  circulating  water  pump  is  driven  by  a  rocking 
beam  from  the  main  engine.  This  supplies  cooling  water  to  the 
cylinder  heads,  and  other  stationary  parts  of  the  engine  and 
compressor.  A  piston-head  cooling  pump,  driven  in  a  similar 
manner  to  the  circulating  pump,  supplies  cooling  water  to  the 
hollow  piston  heads  through  a  system  of  sliding  tubes,  one  of 
which  is  shown  at  F,  Fig.  93. 

The  engines  are  cooled  by  sea  water  when  in  the  open  sea. 
When,  however,  the  ship  is  in  harbor  or  in  a  roadstead,  where  the 
water  available  is  charged  with  organic  matter,  they  are  cooled 
by  a  water  circuit  between  the  engines  and  the  condenser,  the 
latter  being  placed  in  circuit  with  the  harbor  or  roadstead.  The 
water  piping  is  of  copper  of  ample  dimensions,  provided  with  the 
necessary  pressure  gages  and  thermometers. 

General. — The  main  engine  cylinders  are  18.5  inches  in  diam- 
eter, with  a  26.8-inch  stroke.  Fig.  93  shows  the  construction  of 
the  cylinders  with  their  water  jackets.  The  casting  forming  the 
casing  G,  G,  of  the  water  jacket  of  each  cylinder  rests  on  the 
standards  H,  H,  of  the  engine  framing,  and  the  barrel  of  the 
cylinder  /  is  held  by  its  upper  end,  so  that  it  is  free  to  expand 
downwards.  The  cylinder  cover  K,  which  is,  of  course,  water 
cooled,  contains  the  fuel  admission  valve  chamber  L,  and  it  is 
held  in  place  by  four  large  steel  bolts,  M,  M,  which  pass  down 


FiG.  93. — Cross  Section,  Sulzer  Engine. 


THE    DIESEL    ENGINE.  l6l 

alongside  the  cylinder,  through  the  framing  standards,  and  also 
through  the  bed  plate,  as  shown  in  Fig.  93,  and  on  the  left-hand 
side  of  the  plan,  Fig.  91.  These  bolts  thus  take  all  the  tensional 
stresses,  the  standards  of  the  engine  framing  and  the  castings  of 
the  water  jackets  being  always  in  compression. 

The  A-frames,  H,  H,  are  of  close  grained  cast  iron,  and  are  of 
very  substantial  proportions.  They  carry  the  cross  head  guides, 
as  shown  in  Fig.  93.  The  base  plate,  P,  P,  is  also  of  close  grained 
cast  iron,  and  is  made  in  three  parts,  bolted  together,  as  shown 
in  Fig.  91.  Two  of  these  parts  each  carry  the  standards  for  a 
pair  of  cylinders,  the  other  and  forward  part  carrying  the  air 
compressing  pumps.  Bolted  to  the  underside  of  the  bed  plate 
is  a  casting  forming  an  oil  catcher,  into  which  drains  all  the 
surplus  oil  from  the  bearings,  etc.,  this  oil  flowing  thence  to  a 
tank  for  re-use  after  filtering  and  cooling. 

The  lower  half  of  each  crank  shaft  bearing  is  a  steel  shell 
lined  with  white  metal,  and  made  in  cylindrical  form,  so  that  it 
can  be  readily  rolled  out  without  removing  the  shaft.  The  caps 
of  the  bearings  are  of  cast  iron,  and  are  also  lined  with  white 
metal.  The  bolts,  R,  holding  down  the  caps  are  fixed  as  shown 
in  Fig.  93,  so  that  they  are  readily  renewable  if  necessary.  The 
crank  shaft  of  each  set  of  engines  is  in  two  parts,  and  has  the 
cranks  forged  solid.  The  shafts  are  made  of  open  hearth  steel. 
On  the  first  length  of  tail  shaft  coupled  to  the  crank  shaft  is 
mounted  a  flywheel  S,  Fig.  91,  weighing  8  tons. 

The  pistons  are  of  cast  iron,  in  two  parts,  the  upper  part  T 
forming  a  closed  chamber,  through  which  the  water  for  cooling 
is  circulated  by  a  system  of  sliding  tubes  F.  The  lower  part  of 
each  piston  is  simply  a  trunk  U,  as  shown  in  Fig.  93.  The  piston 
rods,  which  are  all  interchangeable,  are  of  open  hearth  steel. 
Each  rod  is  attached  to  its  piston  by  a  flange  V ,  as  shown  in  Fig. 
93,  and  is  bolted  to  the  cross  head.  The  connecting  rods  are  also 
of  open  hearth  steel,  and  their  length  is  4^4  times  the  crank 
radius ;  the  bearings  are  steel  and  bronze  castings  lined  with  white 
metal. 

The  air  for  scavenging  enters  the  working  cylinders  through 
two  horizontal  rows  of  ports,  D,  D,  in  the  cylinder  walls  shown  on 
II 


162  INTERNAL    COMBUSTION    ENGINE    MANUAL. 

the  right  of  the  cylinder,  Fig.  93 ;  the  openings  of  the  lower  row 
are  controlled  by  the  piston  alone,  whilst  the  upper  row  of  open- 
ings is  controlled  by  the  scavenger  valves  and  is  eventually  cov- 
ered by  the  piston.  Air  to  any  desired  quantity  may  be  intro- 
duced into  the  cylinder  through  the  upper  row  of  ports  after  the 
piston  has  closed  the  lower  scavenger  openings. 

The  exhaust  ports,  W,  are  on  the  opposite  side  to  the  scavenger 
ports,  also  in  the  cylinder  walls.  The  exhaust  gases  enter  a  water 
cooled  exhaust  pipe  X,  leading  to  the  muffler,  from  which  they 
escape  freely  into  the  atmosphere.  This  method  of  scavenging 
gives  excellent  results,  and  from  the  point  of  view  of  simplicity 
of  design  and  safety  it  forms  a  decided  improvement  on  other 
methods,  since,  should  a  scavenger  valve  fail,  it  is  impossible  for 
a  charge  to  escape  into  the  exhaust  pipe. 

Auxiliaries. — Each  engine  drives  direct  by  rocking  beams  a 
cooling  water  pump,  a  bilge  pump,  a  sanitary  pump,  a  piston 
head  cooling  pump,  an  oil  fuel  pump,  and  a  pump  for  supplying 
the  oil  for  the  forced  lubrication  of  the  bearings.  The  bilge  and 
sanitary  pumps  are  both  of  the  same  capacity,  and  can  deal  with 
20  tons  of  water  per  hour ;  both  are  of  brass.  Each  engine  has 
its  own  muffler  and  its  own  oil  fuel  tank,  located  in  the  engine- 
room. 

A  compressed  air  jacking  gear  is  provided  at  the  after  end  of 
each  main  engine.  It  gears  into  teeth  cut  into  the  periphery  of  the 
flywheel,  Fig.  91. 

There  are  two  auxiliary  50  horse-power,  three  cylinder,  four 
cycle,  Sulzer-Diesel  engines  in  addition  to  the  above  auxiliaries. 
One  is  coupled  direct  to  a  dynamo  for  lighting  the  ship,  the  other 
drives  an  air  compressor  for  use  in  an  emergency,  such  as  failure 
of  the  normal  air  supply.  When  entering  or  leaving  port,  or  at 
any  'time  when  an.  unusual  amount  of  air  is  required  for  maneu- 
vering, this  compressor  is  run  to  maintain  normal  pressure  at  the 
accumulators. 

Maneuvering  Gear. — The  maneuvering  gear  for  controlling 
each  main  engine  consists  of  two  mechanisms,  each  operated  by  a 
compressed  air  engine  through  a  worm  drive.  One  of  these  en- 
gines serves  to  rotate  the  cam  shaft  through  the  desired  angle 


THE    DIESEL    ENGINE.  163 

with  relation  to  the  crank  shaft,  and  to  put  over  the  scavenger 
pump  valve  rods  into  the  required  position  for  ahead  or  astern 
running.  The  other  serves  to  operate  the  fuel  and  air  starting 
valve  gear,  for  starting,  running,  and  stopping.  All  these  opera- 
tions can  also  be  performed  by  hand  in  case  of  failure  of  the 
maneuvering  engines  for  any  cause  whatsoever.  The  maneuver- 
ing engines  are  in  the  center  of  the  main  engine  fronts,  and  so 
close  together  that  both  engines  can  be  operated  by  one  man. 

The  fuel  valve  and  air  starting  valve  of  each  cylinder  are  all 
operated  by  cams  which  are  keyed  on  one  cam  shaft  common  to 
all  four  cylinders.  For  reversing,  the  engine  is  first  run  in  the 
desired  direction  by  means  of  compressed  air  supplied  through 
the  starting  valves,  the  cam  shaft  being  turned  to  the  required 
angle  in  relation  to  the  main  shaft  so  that  the  lift  of  the  fuel 
valves  takes  place  at  the  right  period  of  the  cycle. 

The  action  of  the  starting  valves  has  to  be  reversible,  so  as  to 
start  the  engine  in  the  required  direction.  To  do  this  there  is 
provided  both  a  forward  and  a  backward  running  cam  for  each 
starting  valve.  A  special  gear  is  provided  for  connecting  the  cam 
rollers  to  or  disconnecting  them  from  the  starting  and  the  fuel 
cams.  Eccentrics  are  fitted  on  the  shaft  in  such  a  manner  that  the 
three  following  positions  can  be  arrived  at:  (1)  Both  sets  of 
cam  rollers  are  out  of  action  when  the  engine  is  at  a  standstill; 

(2)  the  starting  valve  cam  rollers  are  thrown  in,  the  fuel  valve 
cams  being  out,  which  places  the  engine  in  the  starting  position ; 

(3)  the  fuel  valve  cams  are  thrown  in,  the  starting  valve  cams 
being  thrown  out,  which  places  the  engine  in  the  running  position. 
These  positions  are  controlled  by  a  cam  disc  which  thus  controls 
the  engine  when  maneuvering.     To  reverse,  the  engine  is  first 
brought  to  a  standstill;  the  cam  shaft  operating  the  valves  is 
then  turned  to  the  required  position,  ahead  or  astern,  as  the  case 
may  be;  the  air  starting  valves  are  thrown  into  gear,  position  2, 
and  the  engine  starts  and  runs  on  air ;  the  fuel  valves  are  thrown 
into  gear  and  the  air  starting  valves  are  thrown  out  of  gear, 
position  3.     The  engine  is  now  runnning  on  fuel  in  the  desired 
direction. 


INDEX. 


PAGE 

Acetic  acid  in  cylinder 11 

Acetylene,  use  in  engines  of..  14 
Admission,     best    temperature 

for 48 

Advanced  spark  81 

Advantages  of  compression...  42 
Advantages,  relative  of  steam 

and  I.  C.  E 17 

relative    of    two    and    four 

cycle 40 

Aeroplane   engines    116 

Air  cooling    70 

Alcohol   10 

advantages  of  11 

carburetion  of 52 

denatured  10 

engine    115 

thermal  efficiency  of 11 

Anzani  aeroplane  engine 129 

Ashmusen  aeroplane  engine...  127 

Atomizing    vaporizers    50 

Back   firing    94 

Balancing  crank  arms 29 

Beau  de  Rocha's  principle 17 

Benzol    11 

Blast  furnace  gas 13 

Blowing    97 

Booster    59 

Carbon  deposits   73 

knocking   due   to 97 

premature  ignition  due  to..  97 

Carburetor    44 

double  float  type 52 

requirements   of   good 46 

Schebler    46 

troubles     97 

Carburetion  defined 44 

of  air  44 

of  alcohol  52 

of  gas   45 

of  gasoline  45 

of    kerosene    48 

of  oil   51 

spray    45 

surface    45 

Carburizer    44 

Cards,   indicator    .  83 


PAGE 

Charge 44 

Circulating  pump  102 

Classification  of  I.  C.   E., 

cyclic    34 

thermodynamic     43< 

Clearance     16,  99 

Coil  windings, 

four  cylinder  ignition 56 

one  cylinder  ignition   55 

Coke    oven    gas 13 

Cold  point  of  oil.... 73 

Combustion,  progressive   15 

Combustion,    rate    of 15 

Compounding  the  I.  C.  E 18 

Compression    15,  34,  42 

limits    of    43 

lost   97 

Connecting  rod  27 

Constructional    details    23-33 

Cooling  cylinder  by  air 70 

water   68 

Cooling  gases   67 

system    17,  67 

valves,   pistons,   etc 70 

Countershaft 33 

Cracking  process   5 

Crank    chamber   explosions...  97 

Crank   shaft    102 

Crossley   vaporizer    50 

Crude  oil   10 

Crude  still  4,  6 

Cut-off    15 

Cycle  defined 34 

Cycle,  Diesel  140 

four  or  Otto    34 

theoretical 83 

two   or   clerk 34,  36 

Cylinders    23 

air  cooled 23,  70 

copper  jacketed    24 

en  bloc    24 

two    cycle    25 

water  cooled   23 

Diesel  engine 138 

advantages  of  140 

classification   of    138 

cycles    140 


1 66 


INDEX 


PAGE 
Diesel  engine  : 

design    139 

four   cycle    141 

limits  of  power 146 

maximum  temperatures 139 

Nurnberg  type   147 

cooling  and  lubrication . . .  151 

fuel  system   149 

reversing     153 

scavenging    147 

starting    153 

Sulzer  type , 157 

auxiliaries 162 

compressor    157 

cooling 159 

fuel  system    157 

maneuvering  gear   162 

Valve  group,   four  cycle ....  145 

Distillates,   heavy 10 

Distributor    59 

Double  acting  engines 108 

Dual   ignition    64 

Dynamometers    90 

Engine,    aeroplane    116 

Anzani 129 

Ashmusen     127 

characteristics  of  127 

Gnome   132 

Gyro   duplex    134 

Hall  Scott    118 

horizontal  opposed   127 

radial 129 

rotary    '. . .  132 

Sturtevant    123 

vertical 118 

V-type    ' 123 

Wright    126 

Engines : 

alcohol    115 

Diesel    138 

gasoline  101 

kerosene    110 

Knight    112 

Mietz    and    Weiss 110 

Navy  type 101 

Nurnberg   " . .  147 

oil    110 

Standard  double  acting 108 

Standard  submarine  chaser. .  103 

Sulzer    157 

three  port   37 

two  port   37 


PAGE 

Exhaust,   underwater    33 

Explosions,  admission  pipe....  95 

carburetor  96 

crank  case    97 

muffler   96 

weak    96 

Fire    point,    oil 73 

Flame  propagation    15 

Flash  point,  oil 73 

Float   valve   carburetor 46 

Fly  wheel  29 

Forced    feed   lubrication 74 

Fractional  distillation  4 

Franklin    air   cooling 71 

Fuel,    classification   of 1 

selection  of   1 

gaseous    12 

heating  values  of 1-13 

liquid    3 

oil    10,  51 

solid   2 

system     16 

Gas,  acetylene  14 

air    .. 2 

blast  furnace  13 

calorific  value  of 1-3,  12-14 

coke   oven    33 

illuminating    13 

natural     14 

oil    12 

producer   2 

water    "  2 

Gasoline  8,  45 

volatility  as  a  test  for 9 

Generators    58 

Gnome    engine    132 

Governing  by  adjustable  spark      81 

combination  systems  82 

exhaust   82 

hit  and  miss  system 78 

throttling    80 

variable  mixture    81 

varying   compression    82 

Governor,  pick-blade    78 

Governors    and   governing....  77 

Gyro  duplex  aeroplane  engine.  134 

Hall  Scott  aeroplane  engine..  118 

Hammer  break  igniter 62 

Heat   balance    20 

Horizontal  aeroplane  engine..  127 

Horse-power,  brake 90 

indicated,   how   obtained 86 


INDEX 


i67 


PAGE; 

Hot    tube    ignition 65,  110 

Ignition  16,  35,  54 

by  heat  of  compression 66 

comparison  of  different  sys- 
tems   of    63 

double    64 

dual    64 

early  85 

electric    : 54 

faulty     94 

four  cylinder    56,  59 

hammer  break 62 

hot   tube    65,  110 

jump  spark 54 

late   84 

make  and  break 61 

multicylinder   56 

premature    43,  97 

two  point    64 

wipe  spark  61 

Ignition   plugs    54,    62,  63 

Ignition  wiring    55,   56,  61 

Indicators  for  I.  C.  E 86 

Indicator  cards    83 

charge   throttled    84 

faulty  admission    85 

faulty  exhaust 85 

ignition  advanced    85 

ignition  retarded   84 

normal     83 

two  cycle   87 

Induction    cdil    56 

Jacket,    water,    temperature...  67 

Jump  spark  ignition 54 

Kerosene 9 

carburetion   of    48 

engine    110 

Knight   slide  valve  motor 112 

Knocking,  spark,  gas,  and  car 

bon 96 

Late  ignition   84 

Liquid   acetylene    14 

Losses    in    the    I.    C.    E.    and 

steam    engine    20 

Lowe's  process   12 

Lubricating  oil,  characteristics 

of  good  71 

Lubricating    systems    74 

splash    74 

forced   feed    74 

mechanical    feed    74 

small   motors    .  74 


PAGE 

Lubrication    71 

Lubricator,  Detroit   75 

Lunkenheimer  mixing  valve . .  48 

Magneto,    high   tension 58 

low  tension 58 

Make  and  break  ignition 61 

Manograph    . 86 

Maumee 22 

Mechanical  ebullition 45 

Medium     44 

Mietz  and  Weiss  kerosene  en- 
gine   110 

Misfiring,    continuous    95 

intermittent     96 

Mixing  valve    46 

Lunkenheimer    . . .  •. 48 

Mixture,  lean  and  rich 15,  44 

Muffler    30 

ej  ector   31 

explosion     96 

gas  pipe 30 

marine    type    30 

Multicylinder   ignition    56 

Multicylinder   timer    57 

Natural  gas  14 

Navy  type  gasoline  engine...  101 

Normal    indicator   card 83 

Nurnberg    engine    147 

Oil,  cylinder  lubricating 71 

fuel    10,  51 

gas    12 

Operation    92 

Overheating    96 

Petroleum  products    8 

Petroleum,   source,    formation, 

and  composition  of 3 

refining    4 

Pick-blade    governor    78 

Pintsch  oil  gas   producer 12 

Piston    26 

head,  two  cycle  type 27 

lubrication    74 

Plug,   spark   55 

Premature  ignition 43,  97 

Pressure   diagram    98 

Progressive  combustion 15 

Pump,  gas    45 

water    68,  102 

Purification  of  petroleum  dis- 
tillates      7 

Push   rod    28 

Radial  aeroplane  engine 129 


1 68 


INDEX 


PAGE 

Ratio  of  expansion  15 

Reduction    gear    for    counter- 
shaft      33 

Residuum   5 

Rings,    piston    26 

Rotary  aeroplane  engine 132 

Scavenging  the  cylinder 100 

Semi-Diesel    engine    51 

Seven    point    suspension 103 

Shaft,    crank    102 

Smoky  exhaust    97 

Spark  coil   56,  59 

Spark   plug    55 

Splash  lubrication   74 

Splitdorf    timer    57 

Spray  carburetion   45 

Standard     double    acting    en- 
gine      108 

Standard      submarine      chaser 

engine    103 

Start,    failure  to    93 

Stopping  an  I.  C.  E 92 

Starting   on   spark    93 

Still,  crude   4,  6 

Straining  gasoline  98 

Stroke,   long  and   short 17,  98 

Sturtevant  aeroplane  engine..  123 

Submerged  exhaust 33 


PAGE 

Surface  carburetion 45 

Temperatures,    fractional    dis- 
tillation      8 

Thermo    syphon   system 68 

Three  port  engine    37 

Tinier,   Splitdorf    57 

Trouble  hunting    93 

Two   port   engine    37 

Types  of  I.  C.  E 40 

Underwater  exhaust  33 

Valve    gears    28,  32 

Valves   27 

requirements  of  efficient 28 

rotary    28 

Vaporizer,  fuel    50,  107 

Vertical   aeroplane   engine 118 

Viscosity    72 

V-type    aeroplane    engine 123 

Water    cooled    engine 68 

Water   cooled  valves,    pistons, 

etc 70 

Water  gas   2 

Water  jacket 24 

Weak    explosions    96 

Werkspoor  piston   cooling....  69 

Wipe  spark  igniter   61 

Wright  aeroplane  engine 126 

Wrist  pin 27 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 

This  book  is  DUE  on  the  last  date  stamped  below. 

Fine  schedule:  25  cents  on  first  day  overdue 

50  cents  on  fourth  day  overdue 
One  dollar  on  seventh  day  overdue. 


NOV  1 4  1947 
1947 

DEC  3    t947 


ENGINEERING  LIB 


RARY 


LD  21-100m-12,'46(A2012sl6)4120 


Library 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


